Method for preventing or reducing low speed pre-ignition

ABSTRACT

A method for preventing or reducing low speed pre-ignition in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and at least one boron-containing compound, as a minor component. The at least one boron-containing compound includes at least one borated dispersant, or a mixture of a boron-containing compound and a non-borated dispersant. A lubricating engine oil having a composition including a lubricating oil base stock as a major component, and at least one boron-containing compound, as a minor component. The lubricating oils of this disclosure are particularly advantageous as passenger vehicle engine oil (PVEO) products.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/990,764 filed May 9, 2014, herein incorporated by reference in itsentirety.

RELATED APPLICATIONS

This application is related to two other co-pending applications, filedon even date herewith, and identified by the following Attorney Docketnumbers and titles: 2014EM102-US2 entitled “Method for Preventing orReducing Low Speed Pre-Ignition” and 2014EM104-US2 entitled “Method forPreventing or Reducing Low Speed Pre-Ignition”; all of which areincorporated herein in their entirety by reference.

FIELD

This disclosure relates to a method for preventing or reducing low speedpre-ignition (LSPI) in an engine lubricated with a lubricating oil byusing as the lubricating oil a formulated oil that has at least oneboron-containing compound, preferably at least one borated dispersant,or a mixture of a boron-containing compound and a dispersant, present ina particular amount in the formulated oil. The lubricating oils of thisdisclosure are useful as passenger vehicle engine oil (PVEO) products.

BACKGROUND

Pre-ignition in a flame propagation (or “spark-ignition”) enginedescribes an event wherein the air/fuel mixture in the cylinder ignitesbefore the spark plug fires. Pre-ignition is initiated by an ignitionsource other than the spark, such as hot spots in the combustionchamber, a spark plug that runs too hot for the application, orcarbonaceous deposits in the combustion chamber heated to incandescenceby previous engine combustion events.

Many passenger car manufacturers have observed intermittent pre-ignitionin their production turbocharged gasoline engines, particularly at lowspeeds and medium-to-high loads. At these elevated loads, pre-ignitionusually results in severe engine knock that can damage the engine. Thecause of the pre-ignition is not fully understood, and may in fact beattributed to multiple phenomena such as hot deposits within thecombustion chamber, elevated levels of lubricant vapor entering from thePCV system, oil seepage past the turbocharger compressor seals or oiland/or fuel droplet auto-ignition during the compression stroke.

Pre-ignition can sharply increase combustion chamber temperatures andlead to rough engine operation or loss of performance. Traditionalmethods of eliminating pre-ignition include, for example, proper sparkplug selection, proper fuel/air mixture adjustment, and periodiccleaning of the combustion chambers. Hardware solutions such as cooledexhaust gas recirculation (EGR) are known, but these can be costly toimplement and present packaging problems.

Low speed pre-ignition (LSPI) is a type of abnormal combustion affectingengines operating at high brake mean effective pressure (BMEP) and lowengine speed (RPM). This includes internal combustion engines using avariety of fuels, including natural gas, gasoline, diesel, biofuels, andthe like. Downsized, downspeeded, turbocharged engines are mostsusceptible to operating under these engine conditions and are thus moresusceptible to LSPI. As the automobile industry continues to movetowards further downsizing, downspeeding, and increased turbocharging toincrease vehicle fuel economy and reduce carbon dioxide emissions, theconcern over LSPI continues to grow.

The further development of downspeeded, turbocharged gasoline engines isbeing impeded by LSPI. A solution to this problem or even a mitigationof its occurrence would remove barriers for original equipmentmanufacturer (OEM) technology and efficiency improvement. A lubricantformulation solution would enable product differentiation with regard toLSPI.

Although pre-ignition problems can be and are being resolved byoptimization of internal engine components and by the use of newcomponent technology such as electronic controls, modification of thelubricating oil compositions used to lubricate such engines isdesirable. For example, it would be desirable develop new lubricatingoil formulations which are particularly useful in internal combustionengines and, when used in internal combustion engines, will prevent orminimize the pre-ignition problems. It is desired that the lubricatingoil composition be useful in lubricating gasoline-fueled, spark-ignitedengines.

Despite the advances in lubricant oil formulation technology, thereexists a need for an engine oil lubricant that effectively prevents orreduces low speed pre-ignition especially for downsized, downspeeded,turbocharged engines.

SUMMARY

This disclosure relates in part to new lubricating oil formulationswhich are particularly useful in internal combustion engines and, whenused in internal combustion engines will prevent or minimizepre-ignition problems. The lubricating oil compositions of thisdisclosure are useful in lubricating gasoline-fueled, spark-ignitedengines. The lubricant formulation chemistry of this disclosure can beused to prevent or control the detrimental effect of LSPI in engineswhich have already been designed or sold in the marketplace as well asfuture engine technology. The lubricant formulation chemistry of thisdisclosure removes barriers for OEM technology and efficiencyimprovement, and enables further development of downspeeded,turbocharged gasoline engines that is currently being impeded by LSPI.The lubricant formulation solution afforded by this disclosure forpreventing or reducing LSPI enables product differentiation with regardto LSPI.

This disclosure also relates in part to a method for preventing orreducing low speed pre-ignition in an engine lubricated with alubricating oil by using as the lubricating oil a formulated oil. Theformulated oil has a composition comprising a lubricating oil base stockas a major component; and at least one boron-containing compound, as aminor component. The at least one boron-containing compound comprises atleast one borated dispersant, or a mixture of a boron-containingcompound and dispersant. The engine exhibits greater than about 50%reduced low speed pre-ignition, based on normalized low speedpre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at2000 revolutions per minute (RPM) and brake mean effective pressure(BMEP) at 18 bar, as compared to low speed pre-ignition performanceachieved in an engine using a lubricating oil that does not comprise atleast one borated dispersant, or a mixture of a boron-containingcompound and a non-borated dispersant.

This disclosure further relates in part to a method for preventing orreducing low speed pre-ignition in an engine lubricated with lubricatingoil by using as the lubricating oil a formulated oil as described above,in which the minor component further comprises at least one detergent.The detergent comprises at least one alkaline earth metal salt of anorganic acid, and the at least one alkaline earth metal salt of anorganic acid comprises at least one magnesium salt of an organic acid.

This disclosure yet further relates in part to a method for preventingor reducing low speed pre-ignition in an engine lubricated with alubricating oil by using as the lubricating oil a formulated oil asdescribed above, in which the minor component further comprises at leastone detergent, and at least one zinc-containing compound or at least oneantiwear agent. The detergent comprises at least one alkaline earthmetal salt of an organic acid, and the at least one alkaline earth metalsalt of an organic acid comprises at least one magnesium salt of anorganic acid. The at least one antiwear agent comprises at least onezinc dialkyl dithiophosphate compound derived from a secondary alcoholor derived in part from a secondary alcohol.

This disclosure also relates in part to a lubricating engine oil havinga composition comprising a lubricating oil base stock as a majorcomponent; and at least one boron-containing compound, as a minorcomponent. The at least one boron-containing compound comprises at leastone borated dispersant, and/or a mixture of a boron-containing compoundand a non-borated dispersant. The engine exhibits greater than about 50%reduced low speed pre-ignition, based on normalized low speedpre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at2000 revolutions per minute (RPM) and brake mean effective pressure(BMEP) at 18 bar, as compared to low speed pre-ignition performanceachieved in an engine using a lubricating oil that does not comprise atleast one borated dispersant, or a mixture of a boron-containingcompound and a non-borated dispersant.

This disclosure further relates in part to a lubricating engine oil asdescribed above, in which the minor component further comprises at leastone detergent. The detergent comprises at least one alkaline earth metalsalt of an organic acid, and the at least one alkaline earth metal saltof an organic acid comprises at least one magnesium salt of an organicacid.

This disclosure yet further relates in part to a lubricating engine oilas described above, in which the minor component further comprises atleast one detergent, and at least one zinc-containing compound or atleast one antiwear agent. The detergent comprises at least one alkalineearth metal salt of an organic acid, and the at least one alkaline earthmetal salt of an organic acid comprises at least one magnesium salt ofan organic acid. The at least one antiwear agent comprises at least onezinc dialkyl dithiophosphate compound derived from a secondary alcohol.

It has been surprisingly found that, in accordance with this disclosure,prevention or reduction of LSPI can be attained in an engine lubricatedwith a lubricating oil by using as the lubricating oil a formulated oilthat includes at least one boron-containing compound (e.g., boratedsuccinimide), preferably at least one borated dispersant, or a mixtureof a boron-containing compound and a non-borated dispersant, present ina particular amount (e.g., from about 0.1 to about 20 weight percent,based on the total weight of the lubricating oil), in the lubricatingoil. In particular, for lubricating oil formulations containing the atleast one boron-containing compound, it has been surprisingly found thatthe engine exhibits greater than about 50% reduced low speedpre-ignition, based on normalized low speed pre-ignition (LSPI) countsper 25,000 engine cycles, engine operation at 2000 revolutions perminute (RPM) and brake mean effective pressure (BMEP) at 18 bar, ascompared to low speed pre-ignition performance achieved in an engineusing a lubricating oil that does not comprise at least one borateddispersant, or a mixture of a boron-containing compound and anon-borated dispersant In addition, it has been surprisingly found that,in accordance with this disclosure, reduction of LSPI can be attained inan engine lubricated with a lubricating oil by using as the lubricatingoil a formulated oil that has a particular base stock (e.g., agas-to-liquids base stock or an ester base stock).

This disclosure also relates to a method for preventing or reducing lowspeed pre-ignition in an engine lubricated with a lubricating oil byusing as the lubricating oil a formulated engine oil, said formulatedengine oil having a composition comprising at least one lubricating oilbase stock at from 70 to 85 wt. %; and at least one dispersant at aloading to contribute from 30 to 1500 ppm of boron to the formulatedengine oil, wherein said at least one dispersant comprises at least oneborated dispersant, or a mixture of a boron-containing compound and anon-borated dispersant, wherein the engine exhibits greater than 50%reduced low speed pre-ignition, based on normalized low speedpre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at2000 revolutions per minute (RPM) and brake mean effective pressure(BMEP) at 18 bar, as compared to low speed pre-ignition performanceachieved in an engine using a lubricating oil that does not comprise atleast one borated dispersant, or a mixture of a boron-containingcompound and a non-borated dispersant.

Other objects and advantages of the present disclosure will becomeapparent from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

All concentrations indicated in the drawings are quoted on a “asdelivered” basis.

FIG. 1 shows formulation details in weight percent based on the totalweight percent of the formulation, of various lubricating oilformulations, and the results of testing the various lubricating oilformulations, as detailed in Example A.

FIG. 2 graphically depicts thermogravimetric analysis curves for threedifferent dispersants as detailed in Example A.

FIG. 3 shows formulation details in weight percent based on the totalweight percent of the formulation, of various lubricating oilformulations, as detailed in Example B.

FIG. 4 shows the results of testing the various lubricating oilformulations set forth in FIG. 3, as detailed in Example B.

FIG. 5 shows formulation details in weight percent based on the totalweight percent of the formulation, of various lubricating oilformulations, as detailed in Example C.

FIG. 6 shows the results of testing the various lubricating oilformulations set forth in FIG. 5, as detailed in Example C.

FIG. 7 shows formulation details in weight percent based on the totalweight percent of the formulation, of the formulation embodiments ofthis disclosure, as detailed in Example D.

FIG. 8 shows the expected results of testing the various lubricating oilformulations of FIG. 7, as detailed in Example D.

FIG. 9 shows formulation details in weight percent based on the totalweight percent of the formulation, of the formulation embodiments ofthis disclosure, as detailed in Example E.

FIG. 10 shows the expected results of testing the various lubricatingoil formulations of FIG. 9, as detailed in Example E.

FIG. 11 shows formulation details in weight percent based on the totalweight percent of the formulation, of the formulation embodiments ofthis disclosure, as detailed in Example F.

FIG. 12 shows the expected results of testing the various lubricatingoil formulations of FIG. 11, as detailed in Example F.

FIG. 13 shows the results of engine performance mapping as detailed inExample A.

DETAILED DESCRIPTION

All numerical values within the detailed description and the claimsherein are modified by “about” or “approximately” the indicated value,and take into account experimental error and variations that would beexpected by a person having ordinary skill in the art.

It has now been found that prevention or reduction of LSPI can beattained in an engine lubricated with a lubricating oil by using as thelubricating oil a formulated oil that includes at least oneboron-containing compound (e.g., borated succinimide), preferably atleast one borated dispersant, or a mixture of a boron-containingcompound and a non-borated dispersant, present in a particular amount(e.g., from about 0.1 to about 20 weight percent, based on the totalweight of the lubricating oil), in the lubricating oil. In addition, ithas been found that reduction of LSPI can be attained in an enginelubricated with a lubricating oil by using as the lubricating oil aformulated oil that has a particular base stock. The formulated oilpreferably has a composition comprising a lubricating oil base stock asa major component, and at least one boron-containing compound, as aminor component. The at least one boron-containing compound comprises atleast one borated dispersant, or a mixture of a boron-containingcompound and a non-borated dispersant. The lubricating oils of thisdisclosure are particularly advantageous in internal combustion enginesusing a variety of fuels including natural gas, gasoline, diesel,biofuels and the like, and for a variety of applications includingpassenger vehicle engine oils and natural gas engine oils.

The lubricating oils of this disclosure are particularly useful ininternal combustion engines and, when used in internal combustionengines, will prevent or minimize pre-ignition problems. The lubricatingoil compositions of this disclosure are useful in lubricatinggasoline-fueled, spark-ignited engines.

As described herein, the lubricant formulation chemistry of thisdisclosure can be used to prevent or control the detrimental effect ofLSPI in engines which have already been designed or sold in themarketplace as well as future engine technology. The lubricantformulation chemistry of this disclosure removes barriers for OEMtechnology and efficiency improvement, and enables further developmentof downspeeded, turbocharged gasoline engines that is currently beingimpeded by LSPI. The lubricant formulation solution afforded by thisdisclosure for preventing or reducing LSPI enables productdifferentiation with regard to LSPI.

Lubricating Oil Base Stocks

A wide range of lubricating base oils is known in the art. Lubricatingbase oils that are useful in the present disclosure are both naturaloils, and synthetic oils, and unconventional oils (or mixtures thereof)can be used unrefined, refined, or rerefined (the latter is also knownas reclaimed or reprocessed oil). Unrefined oils are those obtaineddirectly from a natural or synthetic source and used without addedpurification. These include shale oil obtained directly from retortingoperations, petroleum oil obtained directly from primary distillation,and ester oil obtained directly from an esterification process. Refinedoils are similar to the oils discussed for unrefined oils except refinedoils are subjected to one or more purification steps to improve at leastone lubricating oil property. One skilled in the art is familiar withmany purification processes. These processes include solvent extraction,secondary distillation, acid extraction, base extraction, filtration,and percolation. Rerefined oils are obtained by processes analogous torefined oils but using an oil that has been previously used as a feedstock.

Groups I, II, III, IV and V are broad base oil stock categoriesdeveloped and defined by the American Petroleum Institute (APIPublication 1509; www.API.org) to create guidelines for lubricant baseoils. Group I base stocks have a viscosity index of between about 80 to120 and contain greater than about 0.03% sulfur and/or less than about90% saturates. Group II base stocks have a viscosity index of betweenabout 80 to 120, and contain less than or equal to about 0.03% sulfurand greater than or equal to about 90% saturates. Group III stocks havea viscosity index greater than about 120 and contain less than or equalto about 0.03% sulfur and greater than about 90% saturates. Group IVincludes polyalphaolefins (PAO). Group V base stock includes base stocksnot included in Groups I-IV. The table below summarizes properties ofeach of these five groups.

Base Oil Properties Saturates Sulfur Viscosity Index Group I <90and/or >0.03% and ≧80 and <120 Group II ≧90 and ≦0.03% and ≧80 and <120Group III ≧90 and ≦0.03% and ≧120 Group IV Includes polyalphaolefins(PAO) Group V All other base oil stocks not included in Groups I, II,III or IV

Natural oils include animal oils, vegetable oils (castor oil and lardoil, for example), and mineral oils. Animal and vegetable oilspossessing favorable thermal oxidative stability can be used. Of thenatural oils, mineral oils are preferred. Mineral oils vary widely as totheir crude source, for example, as to whether they are paraffinic,naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal orshale are also useful. Natural oils vary also as to the method used fortheir production and purification, for example, their distillation rangeand whether they are straight run or cracked, hydrorefined, or solventextracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks,including synthetic oils such as polyalphaolefins, alkyl aromatics andsynthetic esters are also well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oilssuch as polymerized and interpolymerized olefins (polybutylenes,polypro-pylenes, propylene isobutylene copolymers, ethylene-olefincopolymers, and ethylene-alphaolefin copolymers, for example).Polyalphaolefin (PAO) oil base stocks are commonly used synthetichydrocarbon oil. By way of example, PAOs derived from C₆, C₈, C₁₀, C₁₂,C₁₄ olefins or mixtures thereof may be utilized. See U.S. Pat. Nos.4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are knownmaterials and generally available on a major commercial scale fromsuppliers such as ExxonMobil Chemical Company, Chevron Phillips ChemicalCompany, BP, and others, typically vary from about 250 to about 3,000,although PAO's may be made in viscosities up to about 150 cSt (100° C.).The PAOs are typically comprised of relatively low molecular weighthydrogenated polymers or oligomers of alphaolefins which include, butare not limited to, C₂ to about C₃₂ alphaolefins with the C₆ to aboutC₁₆ alphaolefins, such as 1-hexene, 1-octene, 1-decene, 1-dodecene,1-tetradocene, and the like, being preferred. The preferredpolyalphaolefins are poly-1-hexene, poly-1-octene, poly-1-decene andpoly-1-dodecene and mixtures thereof and mixed olefin-derivedpolyolefins. However, the dimers of higher olefins in the range of C₁₄to C₁₈ may be used to provide low viscosity base stocks of acceptablylow volatility. Depending on the viscosity grade and the startingoligomer, the PAOs may be predominantly trimers and tetramers of thestarting olefins, with minor amounts of the higher oligomers, having aviscosity range of 1.5 to 12 cSt. PAO fluids of particular use mayinclude 3.0 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof.Bi-modal mixtures of PAO fluids having a viscosity range of 1.5 to 150cSt may be used if desired.

The PAO fluids may be conveniently made by the polymerization of analphaolefin in the presence of a polymerization catalyst such as theFriedel-Crafts catalysts including, for example, aluminum trichloride,boron trifluoride or complexes of boron trifluoride with water, alcoholssuch as ethanol, propanol or butanol, carboxylic acids or esters such asethyl acetate or ethyl propionate. For example the methods disclosed byU.S. Pat. No. 4,149,178 or 3,382,291 may be conveniently used herein.Other descriptions of PAO synthesis are found in the following U.S. Pat.Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156;4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the C₁₄ toC₁₈ olefins are described in U.S. Pat. No. 4,218,330.

Other useful lubricant oil base stocks include wax isomerate base stocksand base oils, comprising hydroisomerized waxy stocks (e.g. waxy stockssuch as gas oils, slack waxes, fuels hydrocracker bottoms, etc.),hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) base stocksand base oils, and other wax isomerate hydroisomerized base stocks andbase oils, or mixtures thereof. Fischer-Tropsch waxes, the high boilingpoint residues of Fischer-Tropsch synthesis, are highly paraffinichydrocarbons with very low sulfur content. The hydroprocessing used forthe production of such base stocks may use an amorphoushydrocracking/hydroisomerization catalyst, such as one of thespecialized lube hydrocracking (LHDC) catalysts or a crystallinehydrocracking/hydroisomerization catalyst, preferably a zeoliticcatalyst. For example, one useful catalyst is ZSM-48 as described inU.S. Pat. No. 5,075,269, the disclosure of which is incorporated hereinby reference in its entirety. Processes for makinghydrocracked/hydroisomerized distillates andhydrocracked/hydroisomerized waxes are described, for example, in U.S.Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as inBritish Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Eachof the aforementioned patents is incorporated herein in their entirety.Particularly favorable processes are described in European PatentApplication Nos. 464546 and 464547, also incorporated herein byreference. Processes using Fischer-Tropsch wax feeds are described inU.S. Pat. Nos. 4,594,172 and 4,943,672, the disclosures of which areincorporated herein by reference in their entirety.

Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils,and other wax-derived hydroisomerized (wax isomerate) base oils beadvantageously used in the instant disclosure, and may have usefulkinematic viscosities at 100° C. of about 3 cSt to about 50 cSt,preferably about 3 cSt to about 30 cSt, more preferably about 3.5 cSt toabout 25 cSt, as exemplified by GTL 4 with kinematic viscosity of about4.0 cSt at 100° C. and a viscosity index of about 141. TheseGas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils,and other wax-derived hydroisomerized base oils may have useful pourpoints of about −20° C. or lower, and under some conditions may haveadvantageous pour points of about −25° C. or lower, with useful pourpoints of about −30° C. to about −40° C. or lower. Useful compositionsof Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived baseoils, and wax-derived hydroisomerized base oils are recited in U.S. Pat.Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and areincorporated herein in their entirety by reference.

The hydrocarbyl aromatics can be used as base oil or base oil componentand can be any hydrocarbyl molecule that contains at least about 5% ofits weight derived from an aromatic moiety such as a benzenoid moiety ornaphthenoid moiety, or their derivatives. These hydrocarbyl aromaticsinclude alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkylnaphthols, alkyl diphenyl sulfides, alkylated bis-phenol A, alkylatedthiodiphenol, and the like. The aromatic can be mono-alkylated,dialkylated, polyalkylated, and the like. The aromatic can be mono- orpoly-functionalized. The hydrocarbyl groups can also be comprised ofmixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl groups,cycloalkenyl groups and other related hydrocarbyl groups. Thehydrocarbyl groups can range from about C₆ up to about C₆₀ with a rangeof about C₈ to about C₂₀ often being preferred. A mixture of hydrocarbylgroups is often preferred, and up to about three such substituents maybe present. The hydrocarbyl group can optionally contain sulfur, oxygen,and/or nitrogen containing substituents. The aromatic group can also bederived from natural (petroleum) sources, provided at least about 5% ofthe molecule is comprised of an above-type aromatic moiety. Viscositiesat 100° C. of approximately 3 cSt to about 50 cSt are preferred, withviscosities of approximately 3.4 cSt to about 20 cSt often being morepreferred for the hydrocarbyl aromatic component. In one embodiment, analkyl naphthalene where the alkyl group is primarily comprised of1-hexadecene is used. Other alkylates of aromatics can be advantageouslyused. Naphthalene or methyl naphthalene, for example, can be alkylatedwith olefins such as octene, decene, dodecene, tetradecene or higher,mixtures of similar olefins, and the like. Useful concentrations ofhydrocarbyl aromatic in a lubricant oil composition can be about 2% toabout 25%, preferably about 4% to about 20%, and more preferably about4% to about 15%, depending on the application.

Alkylated aromatics such as the hydrocarbyl aromatics of the presentdisclosure may be produced by well-known Friedel-Crafts alkylation ofaromatic compounds. See Friedel-Crafts and Related Reactions, Olah, G.A. (ed.), Inter-science Publishers, New York, 1963. For example, anaromatic compound, such as benzene or naphthalene, is alkylated by anolefin, alkyl halide or alcohol in the presence of a Friedel-Craftscatalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1,chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-sciencePublishers, New York, 1964. Many homogeneous or heterogeneous, solidcatalysts are known to one skilled in the art. The choice of catalystdepends on the reactivity of the starting materials and product qualityrequirements. For example, strong acids such as AlCl₃, BF₃, or HF may beused. In some cases, milder catalysts such as FeCl₃ or SnCl₄ arepreferred. Newer alkylation technology uses zeolites or solid superacids.

Esters comprise a useful base stock. Additive solvency and sealcompatibility characteristics may be secured by the use of esters suchas the esters of dibasic acids with monoalkanols and the polyol estersof mono-carboxylic acids. Esters of the former type include, forexample, the esters of dicarboxylic acids such as phthalic acid,succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid,azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid,linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonicacid, etc., with a variety of alcohols such as butyl alcohol, hexylalcohol, dodecyl alcohol, 2-ethylhexyl alcohol, etc. Specific examplesof these types of esters include dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosylsebacate, etc.

Particularly useful synthetic esters are those which are obtained byreacting one or more polyhydric alcohols, preferably the hinderedpolyols (such as the neopentyl polyols, e.g., neopentyl glycol,trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylolpropane, pentaerythritol and dipentaerythritol) with alkanoic acidscontaining at least about 4 carbon atoms, preferably C₅ to C₃₀ acidssuch as saturated straight chain fatty acids including caprylic acid,capric acid, lauric acid, myristic acid, palmitic acid, stearic acid,arachic acid, and behenic acid, or the corresponding branched chainfatty acids or unsaturated fatty acids such as oleic acid, or mixturesof any of these materials.

Suitable synthetic ester components include the esters of trimethylolpropane, trimethylol butane, trimethylol ethane, pentaerythritol and/ordipentaerythritol with one or more monocarboxylic acids containing fromabout 5 to about 10 or more carbon atoms. These esters are widelyavailable commercially, for example, the Mobil P-41 and P-51 esters ofExxonMobil Chemical Company.

Preferred synthetic esters useful in this disclosure have a kinematicviscosity at 100° C. of about 3 cSt to about 50 cSt, preferably about 3cSt to about 30 cSt, more preferably about 3.5 cSt to about 25 cSt, andeven more preferably about 2 cSt to about 8 cSt. Group V base oilsuseful in this disclosure preferably comprise an ester at aconcentration of about 2% to about 20%, preferably from about 5% toabout 15%.

Also useful are esters derived from renewable material such as coconut,palm, rapeseed, soy, sunflower and the like. These esters may bemonoesters, di-esters, polyol esters, complex esters, or mixturesthereof. These esters are widely available commercially, for example,the Mobil P-51 ester of ExxonMobil Chemical Company.

Engine oil formulations containing renewable esters are included in thisdisclosure. For such formulations, the renewable content of the ester istypically greater than about 70 weight percent, preferably more thanabout 80 weight percent and most preferably more than about 90 weightpercent.

Other useful fluids of lubricating viscosity include non-conventional orunconventional base stocks that have been processed, preferablycatalytically, or synthesized to provide high performance lubricationcharacteristics.

Non-conventional or unconventional base stocks/base oils include one ormore of a mixture of base stock(s) derived from one or moreGas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate basestock(s) derived from natural wax or waxy feeds, mineral and ornon-mineral oil waxy feed stocks such as slack waxes, natural waxes, andwaxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxyraffinate, hydrocrackate, thermal crackates, or other mineral, mineraloil, or even non-petroleum oil derived waxy materials such as waxymaterials received from coal liquefaction or shale oil, and mixtures ofsuch base stocks.

GTL materials are materials that are derived via one or more synthesis,combination, transformation, rearrangement, and/ordegradation/deconstructive processes from gaseous carbon-containingcompounds, hydrogen-containing compounds and/or elements as feed stockssuch as hydrogen, carbon dioxide, carbon monoxide, water, methane,ethane, ethylene, acetylene, propane, propylene, propyne, butane,butylenes, and butynes. GTL base stocks and/or base oils are GTLmaterials of lubricating viscosity that are generally derived fromhydrocarbons; for example, waxy synthesized hydrocarbons, that arethemselves derived from simpler gaseous carbon-containing compounds,hydrogen-containing compounds and/or elements as feed stocks. GTL basestock(s) and/or base oil(s) include oils boiling in the lube oil boilingrange (1) separated/fractionated from synthesized GTL materials such as,for example, by distillation and subsequently subjected to a final waxprocessing step which involves either or both of a catalytic dewaxingprocess, or a solvent dewaxing process, to produce lube oils ofreduced/low pour point; (2) synthesized wax isomerates, comprising, forexample, hydrodewaxed or hydroisomerized cat and/or solvent dewaxedsynthesized wax or waxy hydrocarbons; (3) hydrodewaxed orhydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T)material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possibleanalogous oxygenates); preferably hydrodewaxed orhydroisomerized/followed by cat and/or solvent dewaxing dewaxed F-T waxyhydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (orsolvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials,especially, hydrodewaxed or hydroisomerized/followed by cat and/orsolvent dewaxed wax or waxy feed, preferably F-T material derived basestock(s) and/or base oil(s), are characterized typically as havingkinematic viscosities at 100° C. of from about 2 mm²/s to about 50 mm²/s(ASTM D445). They are further characterized typically as having pourpoints of −5° C. to about −40° C. or lower (ASTM D97). They are alsocharacterized typically as having viscosity indices of about 80 to about140 or greater (ASTM D2270).

The term GTL base stock and/or base oil and/or wax isomerate base stockand/or base oil is to be understood as embracing individual fractions ofsuch materials of wide viscosity range as recovered in the productionprocess, mixtures of two or more of such fractions, as well as mixturesof one or two or more low viscosity fractions with one, two or morehigher viscosity fractions to produce a blend wherein the blend exhibitsa target kinematic viscosity.

The GTL material, from which the GTL base stock(s) and/or base oil(s)is/are derived is preferably an F-T material (i.e., hydrocarbons, waxyhydrocarbons, wax).

In addition, the GTL base stock(s) and/or base oil(s) are typicallyhighly paraffinic (>90% saturates), and may contain mixtures ofmonocycloparaffins and multicycloparaffins in combination withnon-cyclic isoparaffins. The ratio of the naphthenic (i.e.,cycloparaffin) content in such combinations varies with the catalyst andtemperature used. Further, GTL base stock(s) and/or base oil(s) andhydrodewaxed, or hydroisomerized/cat (and/or solvent) dewaxed basestock(s) and/or base oil(s) typically have very low sulfur and nitrogencontent, generally containing less than about 10 ppm, and more typicallyless than about 5 ppm of each of these elements. The sulfur and nitrogencontent of GTL base stock(s) and/or base oil(s) obtained from F-Tmaterial, especially F-T wax, is essentially nil. In addition, theabsence of phosphorous and aromatics make this material especiallysuitable for the formulation of low sulfur, sulfated ash, and phosphorus(low SAP) products.

Base oils for use in the formulated lubricating oils useful in thepresent disclosure are any of the variety of oils corresponding to APIGroup I, Group II, Group III, Group IV, and Group V oils and mixturesthereof, preferably API Group II, Group III, Group IV, and Group V oilsand mixtures thereof, more preferably the Group III to Group V base oilsdue to their exceptional volatility, stability, viscometric andcleanliness features. The above base stocks when used in combinationwith the additive components disclosed in this disclosure can be used toformulate SAE 0W-8, SAE 0W-12, SAE 0W-16, SAE 0W-20, SAE 0W-30, SAE0W-40, SAE 5W-12, SAE 5W-16, SAE 5W-20, SAE 5W-30, and SAE 10W-40products with exceptional LSPI performance. These base stocks when usedin combination with the additive components disclosed in this disclosureare particularly effective in formulating SAE 0W-8, SAE 0W-12, SAE0W-16, SAE 0W-20, SAE 0W-30, SAE 0W-40, and SAE 5W-30 oils withexceptional LSPI performance.

The base oil constitutes the major component of the engine oil lubricantcomposition of the present disclosure and typically is present in anamount ranging from about 50 to about 99 weight percent, preferably fromabout 70 to about 95 weight percent, and more preferably from about 85to about 95 weight percent, based on the total weight of thecomposition. The base oil may be selected from any of the synthetic ornatural oils typically used as crankcase lubricating oils forspark-ignited and compression-ignited engines. The base oil convenientlyhas a kinematic viscosity, according to ASTM standards, of about 2.5 cStto about 12 cSt (or mm²/s) at 100° C. and preferably of about 2.5 cSt toabout 9 cSt (or mm²/s) at 100° C., and more preferably of about 3.5 cStto about 7 cSt (or mm²/s) at 100° C. and even more preferred in someapplications of 3.5 cSt to about 5 cSt (or mm²/s) at 100° C. Mixtures ofsynthetic and natural base oils may be used if desired. Mixtures ofGroup III, IV, and V may be preferably used if desired.

Dispersants

During engine operation, oil-insoluble oxidation byproducts areproduced. Dispersants help keep these byproducts in solution, thusdiminishing their deposition on metal surfaces. Dispersants used in theformulation of the lubricating oil may be ashless or ash-forming innature. Preferably, the dispersant is ashless. So called ashlessdispersants are organic materials that form substantially no ash orlittle ash upon combustion. For example, non-metal-containing or boratedmetal-free dispersants are considered ashless. In contrast,metal-containing detergents discussed above form ash upon combustion.

At least one boron-containing compound is useful in this disclosure. Theboron-containing compound comprises at least one borated dispersant, ora mixture of a boron-containing compound and a non-borated or a borateddispersant. Effective ranges of boron in the formulation from theborated dispersant or other boron containing additive(s) range from 30ppm to 1500 ppm or more preferred range of from 60 ppm to 1000 ppm ormost preferred range of from 120 ppm to 600 ppm.

Preferably, the boron-containing compound includes, for example, aborated succinimide, a borated succinate ester, a borated succinateester amide, a borated Mannich base, and mixtures thereof.

The non-borated dispersant includes, for example, a hydrocarbyl succinicanhydride derived succinimide or succinate ester with a coupling agent,wherein the coupling agent comprises a boron-containing compound.

Preferably, boron is provided to the lubricating oil by a mixture of anorganic or inorganic boron-containing compound and a boratedsuccinimide, and/or boron-containing compound and a hydrocarbylsuccinimide and/or a borated succinimide, a borated succinate ester, aborated succinate ester amide, a Mannich base ester, or mixturesthereof. The borated succinimide is preferably a mono succinimide,bis-succinimide, or a mixture thereof. Effective boron containingcompounds include borated hydrocarbyl succinimides, including thosederived for hydrocarbyl sources where number average molecular weight(M_(n)) is between 50 and 5000 Daltons, borated hydrocarbyl succinates,borated hydrocarbyl substituted Mannich bases, borated alcohols, boratedalkoxylated alcohols, borated hydrocarbyl diols, borated hydrocarbylamines, borated hydrocarbyl diamines, borated hydrocarbyl triamines,borated alkoxylated hydrocarbyl amines, borated alkoxylated hydrocarbylamides, borated hydrocarbyl containing hydroxyl esters, boratedhydrocarbyl substituted oxazolines, borated hydrocarbyl substitutedimidazolones, and the like and mixtures of organic borates. Borates of—N—H, and/or —OH derived moieties can also be used. These borates can beinorganic, or organic moiety derived borates. Borates can be preparedusing boric acid, borated alcohols and the like. These borates can beused at concentrations to provide 30 to 1500 ppm boron, 60-1200 ppmboron in the engine oil formulations, 60-240 ppm boron, 240-1200 ppmboron, 240-500 ppm boron, or 60-120 ppm boron to produce unexpectedsurprising improvement in LSPI performance, as desired.

The ratio of total zinc from the zinc-containing compound and antiwearagent plus total alkaline earth metal from the detergent divided by thetotal boron from the boron-containing compound and borated dispersant,in the lubricating oil, is from about 9.2 to 45, preferably from about11 to 15.

Suitable dispersants typically contain a polar group attached to arelatively high molecular weight hydrocarbon chain. The polar grouptypically contains at least one element of nitrogen, oxygen, orphosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.In some exemplifications, the hydrocarbon chain can range from 6 to 50carbon atoms.

Chemically, many dispersants may be characterized as phenates,sulfonates, sulfurized phenates, salicylates, naphthenates, stearates,carbamates, thiocarbamates, phosphorus derivatives. A particularlyuseful class of dispersants are the alkenylsuccinic derivatives,typically produced by the reaction of a long chain hydrocarbylsubstituted succinic compound, usually a hydrocarbyl substitutedsuccinic anhydride, with a polyhydroxy or polyamino compound. The longchain hydrocarbyl group constituting the oleophilic portion of themolecule which confers solubility in the oil, is normally apolyisobutylene group. Many examples of this type of dispersant are wellknown commercially and in the literature. Exemplary U.S. patentsdescribing such dispersants are U.S. Pat. Nos. 3,172,892; 3,2145,707;3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012;3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersantare described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025;3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574;3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250;3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. Afurther description of dispersants may be found, for example, inEuropean Patent Application No. 471 071, to which reference is made forthis purpose.

Hydrocarbyl-substituted succinic acid and hydrocarbyl-substitutedsuccinic anhydride derivatives are useful dispersants. In particular,succinimide, succinate esters, or succinate ester amides prepared by thereaction of a hydrocarbon-substituted succinic acid compound preferablyhaving at least 50 carbon atoms in the hydrocarbon substituent, with atleast one equivalent of an alkylene amine are particularly useful,although on occasion, having a hydrocarbon substituent between 20-50carbon atoms can be useful.

Succinimides are formed by the condensation reaction between hydrocarbylsubstituted succinic anhydrides and amines. Molar ratios can varydepending on the polyamine. For example, the molar ratio of hydrocarbylsubstituted succinic anhydride to ethylene amines (e.g., Diethylenetriamine, triethylene tetraamine, tetraethylene pentaamine, hexaethyleneheptamine, heptaethylene octaamine, and the like) Polyethylene aminescontaining Tetraethylene Pentaamine (TEPA) are often preferred. Highmolecular weight polyethylene amine bottoms comprising hexaethyleneheptamine, and heptaethylene octaamine can also be used. The ratio ofhydrocarbyl substituted succinic anhydride to polyethylene aminescanvary from about 1:1 to about 5:1. Representative examples are shown inU.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670;and 3,652,616, 3,948,800; and Canada Patent No. 1,094,044.

Succinate esters are formed by the condensation reaction betweenhydrocarbyl substituted succinic anhydrides and alcohols or polyols.Molar ratios can vary depending on the alcohol or polyol used. Forexample, the condensation product of a hydrocarbyl substituted succinicanhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction betweenhydrocarbyl substituted succinic anhydrides and alkanol amines. Forexample, suitable alkanol amines include ethoxylatedpolyalkylpolyamines, propoxylated polyalkylpolyamines andpolyalkenylpolyamines such as polyethylene polyamines. One example ispropoxylated hexamethylenediamine. Representative examples are shown inU.S. Pat. No. 4,426,305.

The molecular weight of the hydrocarbyl substituted succinic anhydridesused in the preceding paragraphs will typically range between 800 and2,500 Daltons or more. The above products can be post-reacted withvarious reagents such as sulfur, oxygen, formaldehyde, carboxylic acidssuch as oleic acid. The above products can also be post reacted withboron compounds such as boric acid, borate esters or highly borateddispersants, to form borated dispersants generally having from about 0.1to about 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols,formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which isincorporated herein by reference. Process aids and catalysts, such asoleic acid and sulfonic acids, can also be part of the reaction mixture.Molecular weights of the alkylphenols range from 800 to 2,500.Representative examples are shown in U.S. Pat. Nos. 3,697,574;3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannichcondensation products useful in this disclosure can be prepared fromhigh molecular weight alkyl-substituted hydroxyaromatics or HN®₂group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are wellknown to one skilled in the art; see, for example, U.S. Pat. Nos.3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197.

Preferred dispersants include borated succinimides, including thosederivatives from mono-succinimides, bis-succinimides, and/or mixtures ofmono- and bis-succinimides, wherein the hydrocarbyl succinimide isderived from a hydrocarbylene group such as polyisobutylene having aM_(n) of from about 500 to about 5000 Daltons, or from about 1000 toabout 3000 Daltons, or about 1000 to about 2000 Daltons, or a mixture ofsuch hydrocarbylene groups, often with high terminal vinylic groups.Preferred dispersants useful in this disclosure are characterized havinga M_(n) of about 800 to 1700 Daltons for low molecular weight, and aM_(n) of about 1700 to about 5000 Daltons or greater for high molecularweight. Other preferred dispersants include succinic acid-esters andamides, alkylphenol-polyamine-coupled Mannich adducts, their cappedderivatives, and other related components. Such additives may be used inan amount of about 0.1 to 20 weight percent, preferably about 0.5 to 8weight percent, or more preferably 0.5 to 4 weight percent. Thehydrocarbon portion of the dispersant atoms can range from C₆₀ to C₄₀₀,or from C₇₀ to C₃₀₀, or from C₇₀ to C₂₀₀. These dispersants may containboth neutral and basic nitrogen, and mixtures of both. The ratio ofbasic to non-basic nitrogen in the dispersant can range from 1 to 5, to5 to 1 or more preferably from 1 to 2, to 2 to 1. Dispersants can beend-capped by borates and/or cyclic carbonates and or any carboxylicacid such as hydrocarbyl carboxylic acids or hydrocarbyl carboxylic acidanhydrides.

In accordance with this disclosure, an engine exhibits greater thanabout 50%, preferably greater than about 70%, and more preferablygreater than about 80%, reduced low speed pre-ignition, based onnormalized low speed pre-ignition (LSPI) counts per 25,000 enginecycles, engine operation at 2000 revolutions per minute (RPM) and brakemean effective pressure (BMEP) at 18 bar, as compared to low speedpre-ignition performance achieved in an engine using a lubricating oilcontaining a minor component other than the at least oneboron-containing compound, and in an amount other than the amount of theat least one boron-containing compound, in the lubricating oil. Similaror even greater reduced low speed pre-ignition can be attained usingmixtures of the at least one boron-containing compound with at least onedetergent, preferably a magnesium containing detergent, and/or with atleast one zinc-containing compound or at least one antiwear agent, asdescribed herein.

As used herein, the dispersant concentrations are given on an “asdelivered” basis. Typically, the active dispersant is delivered with aprocess oil. The “as delivered” dispersant typically contains from about20 weight percent to about 80 weight percent, or from about 40 weightpercent to about 60 weight percent, of active dispersant in the “asdelivered” dispersant product.

Detergents

Illustrative detergents useful in this disclosure include, for example,alkaline earth metal detergents, or mixtures of alkaline earth metaldetergents. A typical alkaline earth metal detergent is an anionicmaterial that contains a long chain hydrophobic portion of the moleculeand a smaller anionic or oleophobic hydrophilic portion of the molecule.The anionic portion of the detergent is derived from an organic acidsuch as a sulfur acid, carboxylic acid, phosphorous acid, phenol, ormixtures thereof. The counterion is an alkaline earth metal. Preferably,the detergent comprises at least one alkaline earth metal salt of anorganic acid, and the at least one alkaline earth metal salt of anorganic acid comprises at least one magnesium salt of an organic acid.

Preferred detergents useful in the lubricating oils of this disclosureare selected from the group consisting of an alkaline earth metalsulfonate, an alkaline earth metal carboxylate (e.g., salicylate), analkaline earth metal phenate, an alkaline earth metal phosphate, andmixtures thereof. The alkaline earth metal sulfonate, alkaline earthmetal carboxylate, alkaline earth metal phenate, alkaline earth metalphosphate, and mixtures thereof, and the amount of the alkaline earthmetal sulfonate, alkaline earth metal carboxylate, alkaline earth metalphenate, alkaline earth metal phosphate, and mixtures thereof in thelubricating oil, are sufficient for the engine to exhibit reduced lowspeed pre-ignition, as compared to low speed pre-ignition performanceachieved in an engine using a lubricating oil containing a detergentother than the alkaline earth metal sulfonate, alkaline earth metalcarboxylate, alkaline earth metal phenate, alkaline earth metalphosphate, and mixtures thereof, and in an amount other than the amountof the alkaline earth metal sulfonate, alkaline earth metal carboxylate,alkaline earth metal phenate, alkaline earth metal phosphate, andmixtures thereof, in the lubricating oil.

The alkaline earth metal detergents useful in this disclosure can beprepared by convention methods known in the art.

Alkaline earth metal sulfonates are a preferred class of detergents.Sulfur acids useful in preparing the alkaline earth metal sulfonatesinclude sulfonic acids, thiosulfonic, sulfinic, sulfenic, partial estersulfuric, sulfurous and thiosulfuric acids. Sulfonic acids arepreferred.

The sulfonic acids are generally petroleum sulfonic acids orsynthetically prepared alkaryl sulfonic acids. Among the petroleumsulfonic acids, the most useful products are those prepared by thesulfonation of suitable petroleum fractions with a subsequent removal ofacid sludge, and purification. Synthetic alkaryl sulfonic acids areprepared usually from alkylated benzenes such as the Friedel-Craftsreaction products of benzene and polymers such as tetrapropylene. Thefollowing are specific examples of sulfonic acids useful in preparingthe alkaline earth metal sulfonate detergents useful in this disclosure.It is to be understood that such examples serve also to illustrate thealkaline earth metal salts of such sulfonic acids. In other words, forevery sulfonic acid enumerated, it is intended that the correspondingbasic alkaline earth metal salts thereof are also understood to beillustrated.

Such sulfonic acids include mahogany sulfonic acids, bright stocksulfonic acids, petrolatum sulfonic acids, mono- and polywax-substitutednaphthalene sulfonic acids, cetylchlorobenzene sulfonic acids,cetylphenol sulfonic acids, cetylphenol disulfide sulfonic acids,cetoxycapryl benzene sulfonic acids, dicetyl thianthrene sulfonic acids,dilauryl beta-naphthol sulfonic acids, dicapryl nitronaphthalenesulfonic acids, saturated paraffin wax sulfonic acids, unsaturatedparaffin wax sulfonic acids, hydroxy-substituted paraffin wax sulfonicacids, tetra-isobutylene sulfonic acids, tetra-amylene sulfonic acids,chloro-substituted paraffin wax sulfonic acids, nitroso-substitutedparaffin wax sulfonic acids, petroleum naphthene sulfonic acids,cetylcyclopentyl sulfonic acids, lauryl cyclohexyl sulfonic acids, mono-and polywax-substituted cyclohexyl sulfonic acids, dodecylbenzenesulfonic acids, “dimer alkylate” sulfonic acids, and the like.

Alkyl-substituted benzene sulfonic acids wherein the alkyl groupcontains at least 8 carbon atoms including dodecyl benzene “bottoms”sulfonic acids are useful in this disclosure. The latter are acidsderived from benzene which has been alkylated with propylene tetramersor isobutene trimers to introduce 1, 2, 3, or more branched-chain C₁₂substituents on the benzene ring. Dodecyl benzene bottoms, principallymixtures of mono- and di-dodecyl benzenes, are available as by-productsfrom the manufacture of household detergents.

Preferred alkaline earth metal sulfonates include magnesium sulfonate,calcium sulfonate, and mixtures thereof.

Alkaline earth phenates are a useful class of detergents. Thesedetergents can be made by reacting alkaline earth metal hydroxide oroxide (CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂, for example) with analkyl phenol or sulfurized alkylphenol. Useful alkyl groups includestraight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀ ormixtures thereof. Examples of suitable phenols include isobutylphenol,2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It shouldbe noted that starting alkylphenols may contain more than one alkylsubstituent that are each independently straight chain or branched andcan be used from 0.5 to 6 weight percent. When a non-sulfurizedalkylphenol is used, the sulfurized product may be obtained by methodswell known in the art. These methods include heating a mixture ofalkylphenol and sulfurizing agent (including elemental sulfur, sulfurhalides such as sulfur dichloride, and the like) and then reacting thesulfurized phenol with an alkaline earth metal base.

Preferred phenate compounds include, for example, magnesium phenate,calcium phenate, an overbased phenate compound, a sulfurized/carbonatedcalcium phenate compound, and mixtures thereof.

Alkaline earth metal salts of carboxylic acids are also useful asdetergents. These carboxylic acid detergents may be prepared by reactinga basic alkaline earth metal compound with at least one carboxylic acidand removing free water from the reaction product. These compounds maybe overbased to produce the desired TBN level.

Detergents made from salicylic acid are one preferred class ofdetergents derived from carboxylic acids. Useful salicylates includelong chain alkyl salicylates. One useful family of compositions is ofthe formula

where R is an alkyl group having 1 to about 30 carbon atoms, n is aninteger from 1 to 4, and M is an alkaline earth metal. Preferred Rgroups are alkyl chains of at least C₁₁, preferably C₁₃ or greater. Rmay be optionally substituted with substituents that do not interferewith the detergent's function. M is preferably, calcium, magnesium, orbarium. More preferably, M is calcium or magnesium.

Hydrocarbyl-substituted salicylic acids may be prepared from phenols bythe Kolbe reaction (see U.S. Pat. No. 3,595,791). The alkaline earthmetal salts of the hydrocarbyl-substituted salicylic acids may beprepared by double decomposition of an alkaline earth metal salt in apolar solvent such as water or alcohol.

Preferred carboxylate compounds comprise a noncarbonated magnesiumsalicylate (carboxylate); a carbonated magnesium salicylate(carboxylate); a noncarbonated calcium salicylate (carboxylate); acarbonated calcium salicylate (carboxylate); and mixtures thereof.

Salts that contain a substantially stoichiometric amount of the alkalineearth metal are described as neutral salts and have a total base number(TBN, as measured by ASTM D2896) of from 0 to 100. Many compositions areoverbased, containing large amounts of a metal base that is achieved byreacting an excess of an alkaline earth metal compound with an acidicgas (such as carbon dioxide). Useful detergents can be neutral, mildlyoverbased, or highly overbased. These detergents can be used in mixturesof neutral, overbased, highly overbased magnesium salicylate,sulfonates, phenates and/or calcium salicylate, sulfonates, andphenates. The TBN ranges can vary from low TBN of about 0 to 100, mediumTBN of about 100 to 200, and high TBN of about 200 to as high as 600.Mixtures of low, medium, high TBN can be used, along with mixtures ofcalcium and magnesium metal based detergents, and including sulfonates,phenates, salicylates, and carboxylates. Further examples of mixed TBNdetergents can be found as described in U.S. Pat. No. 7,704,930, whichis incorporated herein by reference. A detergent mixture with a metalratio of 1, in conjunction of a detergent with a metal ratio of 2, andas high as a detergent with a metal ratio of 5 or 10 or 15, can be used.Borated detergents can also be used.

Alkaline earth metal phosphates may also be used as detergents and areknown in the art.

Detergents may be simple detergents or what is known as hybrid orcomplex detergents. The latter detergents can provide the properties oftwo detergents without the need to blend separate materials. See U.S.Pat. No. 6,034,039.

Suitable detergents include magnesium sulfonates, calcium sulfonates,calcium phenates, magnesium phenates, calcium salicylates, magnesiumsalicylates, and other related components (including borateddetergents), and mixtures thereof. Preferred detergents includemagnesium sulfonate, calcium sulfonate, magnesium phenate, calciumphenate, magnesium salicylate, calcium salicylate, and mixtures thereof.

Other illustrative detergents that may be used in combination with thealkaline earth metal detergents include, for example, alkali metaldetergents, or mixtures of alkali metal detergents.

In a detergent comprising a mixture of a magnesium salt of an organicacid and a calcium salt of an organic acid, the detergent ratio ofmagnesium metal to calcium metal ranges from about 1:0 to about 1:10,preferably from about 1:0 to about 1:4.

The magnesium and alkaline earth metal contributed by the detergent ispresent in the lubricating oil in an amount from about 500 ppm to about5000 ppm, preferably from about 1000 ppm to about 2500 ppm. Themagnesium contributed by the detergent is present in the lubricating oilin an amount from about 100 ppm to about 3000 ppm, preferably from about300 ppm to about 2500 ppm, more preferably from about 750 ppm to about2000 ppm.

The total base number (TBN), as measured by ASTM D2896, contributed bythe detergent ranges from about 2 mg KOH/g to about 17 mg KOH/g,preferably from about 4 mg KOH/g to about 14 mg KOH/g. The TBNcontributed by the magnesium detergent ranges from about 2 mg KOH/g toabout 17 mg KOH/g, preferably from about 3 mg KOH/g to about 14 mgKOH/g, more preferably from about 5 mg KOH/g to about 10 mg KOH/g.

The sulfated ash contributed by the detergent ranges from about 0.4 toabout 1.7 wt %, preferably from about 0.5 to about 1.6 wt %, and morepreferably from about 0.6 to about 1.0 wt %. The sulfated ashcontributed by the magnesium detergent ranges from about 0.3 to about1.8 wt %, preferably from about 0.4 to about 1.6 wt %, and morepreferably from about 0.6 to about 1.0 wt %. The lubricating engine oilof this disclosure preferably contains less than about 1.6 percent byweight sulfated ash and/or more preferably contains less than about 4000ppm of magnesium. At higher engine oil sulfated ash at or above 1.2% ash(with the use of a magnesium detergent) greater than a 95% reduction inLSPI counts is achieved. At sulfated ash levels <1.2% with the use of amagnesium detergent, LSPI can be entirely eliminated.

For lubricating oil formulations containing at least oneboron-containing compound and at least one detergent in accordance withthis disclosure, an engine exhibits greater than about 50%, preferablygreater than about 75%, and more preferably greater than about 95%,reduced low speed pre-ignition, based on normalized low speedpre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at2000 revolutions per minute (RPM) and brake mean effective pressure(BMEP) at 18 bar, as compared to low speed pre-ignition performanceachieved in an engine using a lubricating oil containing a minorcomponent other than the at least one boron-containing compound and atleast one detergent, and in an amount other than the amount of the atleast one boron-containing compound and at least one detergent, in thelubricating oil.

The detergent concentration in the lubricating oils of this disclosurecan range from about 1.0 to about 6.0 weight percent, preferably about2.0 to 5.0 weight percent, and more preferably from about 2.0 weightpercent to about 4.0 weight percent, based on the total weight of thelubricating oil. In the lubricating oils of this disclosure, the amountof alkaline earth metal sulfonate preferably can range from about 0.5 toabout 2.5 weight percent, preferably from about 0.5 to about 2.0 weightpercent, and more preferably from about 0.5 to about 1.5 weight percent,based on the total weight of the lubricating oil. In the lubricatingoils of this disclosure, the amount of alkaline earth metal phenatepreferably can range from about 0.5 to about 2.5 weight percent,preferably from about 0.5 to about 2.0 weight percent, and morepreferably from about 0.5 to about 1.5 weight percent, based on thetotal weight of the lubricating oil. In the lubricating oils of thisdisclosure, the amount of alkaline earth metal carboxylate can rangefrom about 1.0 to about 4.0 weight percent, preferably from about 1.0 toabout 3.0 weight percent, and more preferably from about 1.5 to about2.5 weight percent, based on the total weight of the lubricating oil. Inthe lubricating oils of this disclosure, the amount of alkaline earthmetal phosphate can range from about 1.0 to about 4.0 weight percent,preferably from about 1.0 to about 3.0 weight percent, and morepreferably from about 1.5 to about 2.5 weight percent, based on thetotal weight of the lubricating oil.

As used herein, the detergent concentrations are given on an “asdelivered” basis. Typically, the active detergent is delivered with aprocess oil. The “as delivered” detergent typically contains from about20 weight percent to about 80 weight percent, or from about 40 weightpercent to about 60 weight percent, of active detergent in the “asdelivered” detergent product.

Antiwear Agent

A metal alkylthiophosphate and more particularly a metal dialkyl dithiophosphate in which the metal constituent is zinc, or zinc dialkyl dithiophosphate (ZDDP) is a useful component of the lubricating oils of thisdisclosure. ZDDP can be derived from primary alcohols, secondaryalcohols or mixtures thereof. The preferred ZDDP compounds generally arerepresented by the formula

Zn[SP(S)(OR¹)(OR²)]₂

wherein R¹ and R² are independently primary or secondary C₁ to C₈ alkylgroups. A mixture of primary alcohol (1°) derived ZDDP and secondaryalcohol (2°) derived ZDDP can be used. The R¹ and R² substituents canindependently be C₁-C₁₈ alkyl groups, preferably C₂-C₁₂ alkyl groups.Preferably, R¹ and R² are independently primary or secondary C₁ to C₈alkyl groups, provided at least one of R¹ and R² is a secondary C₁ to C₈alkyl group. Mixtures of primary alcohol derived ZDDP and secondaryalcohol derived ZDDP, where R¹ and R² are C₁ to C₈ alkyl groups can beused. These alkyl groups may be straight chain or branched. Alkyl arylgroups may also be used.

Preferable zinc dithiophosphates which are commercially availableinclude secondary zinc dithiophosphates such as those available from forexample, The Lubrizol Corporation under the trade designations “LZ677A”, “LZ 1095”, “LZ 1389” and “LZ 1371”, from for example ChevronOronite under the trade designation “OLOA 262” from for example AftonChemical under the trade designation “HITEC 7169”, and from for exampleInfineum under the trade designation Infineum C9417, and Infineum C9414.

Preferably, the primary or secondary C₁ to C₈ alkyl groups of the zincdialkyl dithiophosphate compound are derived in part from an alcoholselected from the group consisting of: 2-propanol (C3), 1-butanol(n-C4), 1-isobutanol (1-i-C4), 2-butanol (2-C4), 1-pentanol (primaryC-5), 3-methyl-1-butanol (primary C-5), 2-pentanol (i-05), 3-pentanol(C5), 3-methyl-2-butanol (C5), 1-hexanol (primary C6),4-methyl-1-pentanol (primary C6), 4-methyl-2-pentanol (i-C6), and2-ethyl-1-hexanol (primary C8), and mixtures thereof. In some cases ZDDPderived from alcohols having an average carbon number of 5 and less aredesirable. In some cases ZDDP derived from alcohols having an averagecarbon number of greater than 5 are desirable. Table 1 below showsalcohol mixtures used to make ZDDP which can be advantageously used inthis invention.

TABLE 1 Alcohol Mixtures Useful in Preparing ZDDPs (wt %) i-C3, 2-C4, -1-i-C4, n-C4, - i-C5 n-C5 i-C6 C6 C8 Secondary Secondary Primary PrimarySecondary Primary Secondary Primary Primary 20.2% 4.0% 75.7% 8.4% 3.2%11.7% 76.6% 45.2% 6.2% 19.4% 1.4% 8.8% 19.1% 42.3% 2.4% 55.3% 23.2%13.3% 63.6% 5.7% 2.3% 92.1% 4.6% 63.1% 32.3% 4.1% 2.4% 52.6% 40.9% 7.7%1.8% 90.6% 9.1% 0.4% 89.3% 0.4% 0.8% 42.0% 0.5% 56.5% 0.2% 0.9% 33.9%66.1% 0.3% 0.2% 99.6% 85.6% 14.4%

The R¹ and R² primary or secondary alkyl groups of the zinc dialkyldithiophosphate compound, and the amount of the zinc dialkyldithiophosphate compound having the R¹ and R² primary or secondary alkylgroups in the lubricating oil, are sufficient for an engine to exhibitreduced low speed pre-ignition, as compared to low speed pre-ignitionperformance achieved in an engine using a lubricating oil containing aminor component other than the particular zinc dialkyl dithiophosphatecompound, and in an amount other than the amount of the particular zincdialkyl dithiophosphate compound, in the lubricating oil.

In general, the ZDDP can be used in amounts of from about 0.4 weightpercent to about 1.2 weight percent, preferably from about 0.5 weightpercent to about 1.0 weight percent, and more preferably from about 0.6weight percent to about 0.8 weight percent, based on the total weight ofthe lubricating oil, although more or less can often be usedadvantageously. Preferably, the ZDDP is a mixture of a primary alcoholderived ZDDP and, secondary alcohol derived ZDDP or a ZDDP derived froma mixture of primary alcohols and secondary alcohols, and present in anamount of from about 0.6 to 1.0 weight percent of the total weight ofthe lubricating oil.

Preferably, the zinc dialkyl dithiophosphate compounds having the R¹ andR² primary or secondary alkyl groups, in which the R¹ and R² primary orsecondary alkyl groups are derived from 2-ethyl-1-hexanol (Primary C8),are present in an amount of from about 0.1 weight percent to about 5.0weight percent, preferably from about 0.1 to about 1.2 weight percent,and more preferably from about 0.2 to about 0.8 weight percent, based onthe total weight of the lubricating oil.

Preferably, the zinc dialkyl dithiophosphate compounds having the R¹ andR² primary or secondary alkyl groups, in which the R¹ and R² primary orsecondary alkyl groups are derived from 4-methyl-2-pentanol (C6), arepresent in an amount of from about 0.1 weight percent to about 5.0weight percent, preferably from about 0.1 to about 1.2 weight percent,and more preferably from about 0.2 to about 0.8 weight percent, based onthe total weight of the lubricating oil.

Preferably, the zinc dialkyl dithiophosphate compound is derived from aC₃ to C₈ secondary alcohol, or a mixture thereof. Also, preferably, thezinc dialkyl dithiophosphate compound is derived from a mixture of a C₁to C₈ primary alcohol and a C₁ to C₈ secondary alcohol.

The zinc content contributed by the zinc-containing compound or antiwearagent in the lubricating oil ranges from about 500 ppm to about 2000ppm, preferably from about 600 ppm to about 900 ppm.

The phosphorus content contributed by the zinc-containing compound orantiwear agent in the lubricating oil ranges from about 400 ppm to about2000 ppm, preferably from about 500 ppm to about 900 ppm. The phosphorusderived from the secondary ZDDP is preferably from 0 to 900 ppm and morepreferably from 400 to 900 ppm.

The zinc to phosphorus ratio in the lubricating oil ranges from about1.0 to about 2.0, preferably from about 1.05 to about 1.9.

The ratio of total metals provided by the detergent to total metalsprovided by the zinc-containing compound and antiwear agent is fromabout 0.8 to 4.8, preferably from about 1.4 to 4.0, and more preferablyfrom about 1.5 to 3.7.

Illustrative zinc-containing compounds useful in this disclosureinclude, for example, zinc sulfonates, zinc carboxylates, zinc acetates,zinc napthenates, zinc alkenyl succinates, zinc acid phosphate salts,zinc phenates, zinc salicylates, and the like.

For lubricating oil formulations containing at least oneboron-containing compound and the at least one zinc-containing compoundor antiwear agent in accordance with this disclosure, an engine exhibitsgreater than about 20%, preferably greater than about 25%, and morepreferably greater than about 30%, reduced low speed pre-ignition, basedon normalized low speed pre-ignition (LSPI) counts per 25,000 enginecycles, engine operation at 2000 revolutions per minute (RPM) and brakemean effective pressure (BMEP) at 18 bar, as compared to low speedpre-ignition performance achieved in an engine using a lubricating oilcontaining a minor component other than the at least oneboron-containing compound and the at least one zinc-containing compoundor antiwear agent, and in an amount other than the amount of the atleast one boron-containing compound and the at least one zinc-containingcompound or antiwear agent, in the lubricating oil.

Also, for lubricating oil formulations containing at least oneboron-containing compound, at least one detergent, and at least onezinc-containing compound or antiwear agent in accordance with thisdisclosure, an engine exhibits greater than about 50%, preferablygreater than about 75%, and more preferably greater than about 95%,reduced low speed pre-ignition, based on normalized low speedpre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at2000 revolutions per minute (RPM) and brake mean effective pressure(BMEP) at 18 bar, as compared to low speed pre-ignition performanceachieved in an engine using a lubricating oil containing a minorcomponent other than the at least one boron-containing compound, atleast one detergent, and at least one zinc-containing compound orantiwear agent, and in an amount other than the amount of the at leastone boron-containing compound, at least one detergent, and at least onezinc-containing compound or antiwear agent, in the lubricating oil.

Preferably, the zinc dialkyl dithiophosphate compounds having the R¹ andR² primary or secondary alkyl groups, in which the R¹ and R² primary orsecondary alkyl groups are derived from 2-propanol (C3), 2-butanol(2-C4), 1-iso-butanol (1-i-C4), or n-pentanol (n-05), are present in anamount of from about 0.1 weight percent to about 5.0 weight percent,preferably from about 0.1 to about 1.2 weight percent, and morepreferably from about 0.2 to about 0.8 weight percent, based on thetotal weight of the lubricating oil.

The zinc-containing compound or antiwear agent concentration in thelubricating oils of this disclosure can range from about 0.1 to about5.0 weight percent, preferably about 0.2 to 2.0 weight percent, and morepreferably from about 0.2 weight percent to about 1.0 weight percent,based on the total weight of the lubricating oil. In the presence ofmagnesium detergents and boron containing additives, only small amountsof ZDDP is needed to give exceptionally low LSPI counts. In suchpresence of magnesium and boron containing compounds as little as 0.1%to 1.0% ZDDP (100 ppm P to 1000 ppm P phosphorus in the formulatedengine oil) will provide unexpected improvements in LSPI performance. Athigher ash levels and higher TBN levels, ZDDP levels of 1.1 to 4.0% canprovide unexpected improvements in LSPI performance. For SAE xW-40 andxW-50 oils (x=0, 5, 10, 15), ZDDP levels of 1.1 to 4.0% are especiallyuseful to provide unexpected improvements in LSPI performance.

Other Additives

The formulated lubricating oil useful in the present disclosure mayadditionally contain one or more of the other commonly used lubricatingoil performance additives including but not limited to other antiwearagents, other dispersants, other detergents, corrosion inhibitors, rustinhibitors, metal deactivators, extreme pressure additives, anti-seizureagents, wax modifiers, viscosity index improvers, viscosity modifiers,fluid-loss additives, seal compatibility agents, friction modifiers,lubricity agents, anti-staining agents, chromophoric agents, defoamants,demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents,tackiness agents, colorants, and others. For a review of many commonlyused additives, see Klamann in Lubricants and Related Products, VerlagChemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0. Reference is alsomade to “Lubricant Additives” by M. W. Ranney, published by Noyes DataCorporation of Parkridge, N.J. (1973); see also U.S. Pat. No. 7,704,930,the disclosure of which is incorporated herein in its entirety. Theseadditives are commonly delivered with varying amounts of diluent oil,that may range from 5 weight percent to 50 weight percent.

The types and quantities of performance additives used in combinationwith the instant disclosure in lubricant compositions are not limited bythe examples shown herein as illustrations.

Viscosity Index Improvers

Viscosity index improvers (also known as VI improvers, viscositymodifiers, and viscosity improvers) can be included in the lubricantcompositions of this disclosure.

Viscosity index improvers provide lubricants with high and lowtemperature operability. These additives impart shear stability atelevated temperatures and acceptable viscosity at low temperatures.

Suitable viscosity index improvers include high molecular weighthydrocarbons, polyesters and viscosity index improver dispersants thatfunction as both a viscosity index improver and a dispersant. Typicalmolecular weights of these polymers are between about 10,000 to1,500,000, more typically about 20,000 to 1,200,000, and even moretypically between about 50,000 and 1,000,000.

Examples of suitable viscosity index improvers are linear or star-shapedpolymers and copolymers of methacrylate, butadiene, olefins, oralkylated styrenes. Polyisobutylene is a commonly used viscosity indeximprover. Another suitable viscosity index improver is polymethacrylate(copolymers of various chain length alkyl methacrylates, for example),some formulations of which also serve as pour point depressants. Othersuitable viscosity index improvers include copolymers of ethylene andpropylene, hydrogenated block copolymers of styrene and isoprene, andpolyacrylates (copolymers of various chain length acrylates, forexample). Specific examples include styrene-isoprene orstyrene-butadiene based polymers of 50,000 to 200,000 molecular weight.

Olefin copolymers, are commercially available from Chevron OroniteCompany LLC under the trade designation “PARATONE®” (such as “PARATONE®8921” and “PARATONE® 8941”); from Afton Chemical Corporation under thetrade designation “HiTEC®” (such as “HiTEC® 5850B”; and from TheLubrizol Corporation under the trade designation “Lubrizol® 7067C”.Polyisoprene polymers are commercially available from InfineumInternational Limited, e.g. under the trade designation “SV200”;diene-styrene copolymers are commercially available from InfineumInternational Limited, e.g. under the trade designation “SV 260”.

In an embodiment of this disclosure, the viscosity index improvers maybe used in an amount of less than about 2.0 weight percent, preferablyless than about 1.0 weight percent, and more preferably less than about0.5 weight percent, based on the total weight of the formulated oil orlubricating engine oil. Viscosity improvers are typically added asconcentrates, in large amounts of diluent oil.

In another embodiment of this disclosure, the viscosity index improversmay be used in an amount of from 0.25 to about 2.0 weight percent,preferably 0.15 to about 1.0 weight percent, and more preferably 0.05 toabout 0.5 weight percent, based on the total weight of the formulatedoil or lubricating engine oil.

Antioxidants

Antioxidants retard the oxidative degradation of base oils duringservice. Such degradation may result in deposits on metal surfaces, thepresence of sludge, or a viscosity increase in the lubricant. Oneskilled in the art knows a wide variety of oxidation inhibitors that areuseful in lubricating oil compositions. See, Klamann in Lubricants andRelated Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197,for example.

Useful antioxidants include hindered phenols. These phenolicantioxidants may be ashless (metal-free) phenolic compounds or neutralor basic metal salts of certain phenolic compounds. Typical phenolicantioxidant compounds are the hindered phenolics which are the oneswhich contain a sterically hindered hydroxyl group, and these includethose derivatives of dihydroxy aryl compounds in which the hydroxylgroups are in the o- or p-position to each other. Typical phenolicantioxidants include the hindered phenols substituted with C₆+ alkylgroups and the alkylene coupled derivatives of these hindered phenols.Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol;2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol;2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol;2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecylphenol. Other useful hindered mono-phenolic antioxidants may include forexample hindered 2,6-di-alkyl-phenolic propionic ester derivatives.Bis-phenolic antioxidants may also be advantageously used in combinationwith the instant disclosure. Examples of ortho-coupled phenols include:2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol);and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenolsinclude for example 4,4′-bis(2,6-di-t-butyl phenol) and4,4′-methylene-bis(2,6-di-t-butyl phenol).

Effective amounts of one or more catalytic antioxidants may also beused. The catalytic antioxidants comprise an effective amount of a) oneor more oil soluble polymetal organic compounds; and, effective amountsof b) one or more substituted N,N′-diaryl-o-phenylenediamine compoundsor c) one or more hindered phenol compounds; or a combination of both b)and c). Catalytic antioxidants are more fully described in U.S. Pat. No.8,048,833, herein incorporated by reference in its entirety.

Non-phenolic oxidation inhibitors which may be used include aromaticamine antioxidants and these may be used either as such or incombination with phenolics. Typical examples of non-phenolicantioxidants include: alkylated and non-alkylated aromatic amines suchas aromatic monoamines of the formula R⁸R⁹R¹⁰N where R⁸ is an aliphatic,aromatic or substituted aromatic group, R⁹ is an aromatic or asubstituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)_(x)R¹²where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is ahigher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1or 2. The aliphatic group R⁸ may contain from 1 to 20 carbon atoms, andpreferably contains from 6 to 12 carbon atoms. The aliphatic group is asaturated aliphatic group. Preferably, both R⁸ and R⁹ are aromatic orsubstituted aromatic groups, and the aromatic group may be a fused ringaromatic group such as naphthyl. Aromatic groups R⁸ and R⁹ may be joinedtogether with other groups such as S.

Typical aromatic amines antioxidants have alkyl substituent groups of atleast 6 carbon atoms. Examples of aliphatic groups include hexyl,heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups willnot contain more than 14 carbon atoms. The general types of amineantioxidants useful in the present compositions include diphenylamines,phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenylphenylene diamines. Mixtures of two or more aromatic amines are alsouseful. Polymeric amine antioxidants can also be used. Particularexamples of aromatic amine antioxidants useful in the present disclosureinclude: p,p′-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine;phenyl-alphanaphthylamine; and p-octylphenyl-alpha-naphthylamine.

Sulfurized alkyl phenols and alkali or alkaline earth metal saltsthereof also are useful antioxidants.

Preferred antioxidants include hindered phenols, arylamines. Theseantioxidants may be used individually by type or in combination with oneanother. Such additives may be used in an amount of 0.01 to 5 weightpercent, preferably 0.01 to 2 weight percent, more preferably zero to1.5 weight percent, more preferably zero to less than 1 weight percent.

Pour Point Depressants (PPDs)

Conventional pour point depressants (also known as lube oil flowimprovers) may be added to the compositions of the present disclosure ifdesired. These pour point depressant may be added to lubricatingcompositions of the present disclosure to lower the minimum temperatureat which the fluid will flow or can be poured. Examples of suitable pourpoint depressants include polymethacrylates, polyacrylates,polyarylamides, condensation products of haloparaffin waxes and aromaticcompounds, vinyl carboxylate polymers, and terpolymers ofdialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers.U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655,479;2,666,746; 2,721,877; 2,721,878; and 3,250,715 describe useful pourpoint depressants and/or the preparation thereof. Such additives may beused in an amount of about 0.01 to 5 weight percent, preferably about0.01 to 1.5 weight percent.

Seal Compatibility Agents

Seal compatibility agents help to swell elastomeric seals by causing achemical reaction in the fluid or physical change in the elastomer.Suitable seal compatibility agents for lubricating oils include organicphosphates, alkoxysulfolanes, aromatic esters, aromatic hydrocarbons,esters (butylbenzyl phthalate, for example), and polybutenyl succinicanhydride. Such additives may be used in an amount of about 0.01 to 3weight percent, preferably about 0.01 to 2 weight percent.

Antifoam Agents

Anti-foam agents may advantageously be added to lubricant compositions.These agents retard the formation of stable foams. Silicones and organicpolymers are typical anti-foam agents. For example, polysiloxanes, suchas silicon oil or polydimethyl siloxane, provide antifoam properties.Anti-foam agents are commercially available and may be used inconventional minor amounts along with other additives such asdemulsifiers; usually the amount of these additives combined is lessthan 1 weight percent and often less than 0.1 weight percent.

Inhibitors and Antirust Additives

Antirust additives (or corrosion inhibitors) are additives that protectlubricated metal surfaces against chemical attack by water or othercontaminants. A wide variety of these are commercially available.

One type of antirust additive is a polar compound that wets the metalsurface preferentially, protecting it with a film of oil. Another typeof antirust additive absorbs water by incorporating it in a water-in-oilemulsion so that only the oil touches the metal surface. Yet anothertype of antirust additive chemically adheres to the metal to produce anon-reactive surface. Examples of suitable additives include zincdithiophosphates, metal phenolates, basic metal sulfonates, fatty acidsand amines. Such additives may be used in an amount of about 0.01 to 5weight percent, preferably about 0.01 to 1.5 weight percent.

Friction Modifiers

A friction modifier is any material or materials that can alter thecoefficient of friction of a surface lubricated by any lubricant orfluid containing such material(s). Friction modifiers, also known asfriction reducers, or lubricity agents or oiliness agents, and othersuch agents that change the ability of base oils, formulated lubricantcompositions, or functional fluids, to modify the coefficient offriction of a lubricated surface may be effectively used in combinationwith the base oils or lubricant compositions of the present disclosureif desired. Friction modifiers that lower the coefficient of frictionare particularly advantageous in combination with the base oils and lubecompositions of this disclosure.

Illustrative friction modifiers may include, for example, organometalliccompounds or materials, or mixtures thereof. Illustrative organometallicfriction modifiers useful in the lubricating engine oil formulations ofthis disclosure include, for example, molybdenum amine, molybdenumdiamine, an organotungstenate, a molybdenum dithiocarbamate, molybdenumdithiophosphates, molybdenum amine complexes, molybdenum carboxylates,and the like, and mixtures thereof. Similar tungsten based compounds maybe preferable.

Other illustrative friction modifiers useful in the lubricating engineoil formulations of this disclosure include, for example, alkoxylatedfatty acid esters, alkanolamides, polyol fatty acid esters, boratedglycerol fatty acid esters, fatty alcohol ethers, and mixtures thereof.

Illustrative alkoxylated fatty acid esters include, for example,polyoxyethylene stearate, fatty acid polyglycol ester, and the like.These can include polyoxypropylene stearate, polyoxybutylene stearate,polyoxyethylene isosterate, polyoxypropylene isostearate,polyoxyethylene palmitate, and the like.

Illustrative alkanolamides include, for example, lauric aciddiethylalkanolamide, palmic acid diethylalkanolamide, and the like.These can include oleic acid diethyalkanolamide, stearic aciddiethylalkanolamide, oleic acid diethylalkanolamide, polyethoxylatedhydrocarbylamides, polypropoxylated hydrocarbylamides, and the like.

Illustrative polyol fatty acid esters include, for example, glycerolmono-oleate, saturated mono-, di-, and tri-glyceride esters, glycerolmono-stearate, and the like. These can include polyol esters,hydroxyl-containing polyol esters, and the like.

Illustrative borated glycerol fatty acid esters include, for example,borated glycerol mono-oleate, borated saturated mono-, di-, andtri-glyceride esters, borated glycerol mono-sterate, and the like. Inaddition to glycerol polyols, these can include trimethylolpropane,pentaerythritol, sorbitan, and the like. These esters can be polyolmonocarboxylate esters, polyol dicarboxylate esters, and on occasionpolyoltricarboxylate esters. Preferred can be the glycerol mono-oleates,glycerol dioleates, glycerol trioleates, glycerol monostearates,glycerol distearates, and glycerol tristearates and the correspondingglycerol monopalmitates, glycerol dipalmitates, and glyceroltripalmitates, and the respective isostearates, linoleates, and thelike. On occasion the glycerol esters can be preferred as well asmixtures containing any of these. Ethoxylated, propoxylated, butoxylatedfatty acid esters of polyols, especially using glycerol as underlyingpolyol can be preferred.

Illustrative fatty alcohol ethers include, for example, stearyl ether,myristyl ether, and the like. Alcohols, including those that have carbonnumbers from C₃ to C₅₀, can be ethoxylated, propoxylated, or butoxylatedto form the corresponding fatty alkyl ethers. The underlying alcoholportion can preferably be stearyl, myristyl, C₁₁-C₁₃ hydrocarbon, oleyl,isosteryl, and the like.

Useful concentrations of friction modifiers may range from 0.01 weightpercent to 5 weight percent, or about 0.1 weight percent to about 2.5weight percent, or about 0.1 weight percent to about 1.5 weight percent,or about 0.1 weight percent to about 1 weight percent. Concentrations ofmolybdenum-containing materials are often described in terms of Mo metalconcentration. Advantageous concentrations of Mo may range from 25 ppmto 700 ppm or more, and often with a preferred range of 50-200 ppm.Friction modifiers of all types may be used alone or in mixtures withthe materials of this disclosure. Often mixtures of two or more frictionmodifiers, or mixtures of friction modifier(s) with alternate surfaceactive material(s), are also desirable.

When lubricating oil compositions contain one or more of the additivesdiscussed above, the additive(s) are blended into the composition in anamount sufficient for it to perform its intended function. Typicalamounts of such additives useful in the present disclosure are shown inTable 1 below.

It is noted that many of the additives are shipped from the additivemanufacturer as a concentrate, containing one or more additivestogether, with a certain amount of base oil diluents. Accordingly, theweight amounts in the table below, as well as other amounts mentionedherein, are directed to the amount of active ingredient (that is thenon-diluent portion of the ingredient). The weight percent (wt %)indicated below is based on the total weight of the lubricating oilcomposition.

TABLE 2 Typical Amounts of Other Lubricating Oil Components ApproximateApproximate wt % wt % Compound (Useful) (Preferred) Dispersant  0.1-200.1-8  Detergent  0.1-20 0.1-8  Friction Modifier 0.01-5  0.01-1.5Antioxidant 0.1-5  0.1-1.5 Pour Point Depressant 0.0-5 0.01-1.5 (PPD)Anti-foam Agent 0.001-3  0.001-0.15 Viscosity Index Improver 0.1-20.1-1  (solid polymer basis) Anti-wear 0.1-2 0.5-1  Inhibitor andAntirust 0.01-5  0.01-1.5

The foregoing additives are all commercially available materials. Theseadditives may be added independently but are usually precombined inpackages which can be obtained from suppliers of lubricant oiladditives. Additive packages with a variety of ingredients, proportionsand characteristics are available and selection of the appropriatepackage will take the requisite use of the ultimate composition intoaccount.

Formulated engine oils of the instant disclosure exhibit substantialelimination of LSPI. Substantial elimination of LSPI means greater thanabout 95%, or greater than about 97%, or greater than about 99% reducedlow speed pre-ignition, based on normalized low speed pre-ignition(LSPI) counts per 25,000 engine cycles, engine operation at 2000revolutions per minute (RPM) and brake mean effective pressure (BMEP) at18 bar.

Formulated engine oils with higher ash levels of 1.2 to 1.6% or more inconjunction with the other components disclosed in this disclosure cansignificantly reduce the number of LSPI events by 96% or more.Formulated engine oils with lower ash levels of 0.2 to 1.2% inconjunction with the other components disclosed in this disclosure canreduce the number of LSPI events entirely.

Engines that are highly susceptible to Low speed pre-ignition (LSPI) arethose which operate at high brake mean effective pressure (BMEP) and lowengine speed (RPM). This includes internal combustion engines using avariety of fuels, including natural gas, gasoline, diesel, biofuels, andthe like. Downsized, downspeeded, forced-induction (eg. Turbocharged)engines are most susceptible to operating under these engine conditionsand are thus more susceptible to LSPI. Non-limiting examples of enginespossessing these characteristics include the GM Ecotec and Ford EcoBoostfamily of engines as well as other high BMEP (capable of >10 bar)engines with displacements ranging from about 1 L to about 6 L as wellas engines possessing between 2-10 combustion cylinders in geometricconfigurations including inline, flat (Boxer), and “V” (eg “V8”,“in-line 3”, “in-line 4”, “flat 4” etc.). Furthermore the calibrationand operational setpoints of the engine may significantly influence boththe frequency and severity of LSPI events.

The following non-limiting examples are provided to illustrate thedisclosure.

Examples Example A

Formulations were prepared as described in FIG. 1. All of theingredients used herein are commercially available. Group III, IV and Vbase stocks were used in the formulations. The dispersants used in theformulations were a borated succinimide (which comprised a boratedpolyisobutenyl succinimede with a B/N ratio equal to about 0.5), a highmolecular weight succinimide (High MW Succinimide Dispersant 1 whichcomprised an ethylene carbonate-capped bis-polyisobutenyl succinimidedispersant with about 1% total nitrogen) and a high molecular weightsuccinimide (High MW Succinimide Dispersant 2 which comprised abis-polyisobutenyl succinimde with about 1.2% total nitrogen).

The remaining ingredients used in the formulations were one or more of aviscosity index improver, antioxidant, dispersant, anti-wear agent, pourpoint depressant, corrosion inhibitor, metal deactivator, sealcompatibility additive, anti-foam agent, inhibitor, anti-rust additive,and friction modifier.

Testing was conducted for formulations described in FIG. 1. The resultsare set forth in FIG. 1. Sulfated ash testing was determined inaccordance with ASTM D874. Boron content was determined in accordancewith ASTM D6443. Nitrogen content was determined in accordance with ASTMD3228.

Different engine hardware and control schemes can significantlyinfluence the occurrence of LSPI. See, for example, U.S. PatentApplication Publication Nos. 2012/1866225 and 2003/0908070, and also SAE2012-02-1148, SAE 2011-01-0340, and SAE 2011-01-0343, which are allincorporated herein by reference. Furthermore, FIG. 13 shows drive cycledata obtained from a taxi cab field trial. Two different 2.0 L L4 TGDIengine types, from different Original Equipment Manufacturers weredriven in a typical taxi cab city drive cycle for 2 weeks. Engineperformance data was collected using the vehicles' OBD-II data ports andmapped onto the published engine torque maps for the respective engines.As published in SAE 2011-01-0339, engines are specifically prone to LSPIwhen they operate in a region above 10 bar BMEP and below 3000 rpmengine speed. Therefore, any region of the torque maps for these engineswhich is bounded by these operating conditions is potentially prone toLSPI. Based on the measured data for the OBD-II data loggers, it can beshown that engines with different calibrations can exhibit differentLSPI behavior based on how they are tuned. FIG. 13 shows approximately1.2 million data points summarizing the operation of two differentengine types in a typical taxi cab city driving cycle over a 2 weekperiod. Several taxi cabs using each engine type were observed in thismanner. Engine Make 1 spends on average 1.67% of its operating time inthe LSPI “danger zone” while Engine Make 2 only spends on average 0.17%in a typical taxi cab city drive cycle, even though both engines are 2.0L inline 4-cylinder TGDI engines. Furthermore, Engine Make 2 hasexhibited zero LSPI related field failures, while Engine Make 1 hasexhibited multiple failures related to LSPI. This further illustratesthe different responsiveness of different engine platforms to LSPI.

For the purposes of this disclosure, a 2.0 L, 4-cylinder TGDI GM Ecotecengine was used for LSPI testing. A six segment test procedure was usedto determine the number of LSPI events that occurred at two differentspecified engine load and speed conditions. Each segment of the testprocedure comprised 25,000 engine cycles, where one cycle corresponds to720 degrees of crank shaft rotation. The first set of conditions was2000 RPM and 18 bar BMEP, hereafter referred to as “High Load”. Thesecond set of conditions was 1500 RPM and 12.5 bar BMEP, hereafterreferred to as “Low Load”. The test procedure comprised two segments ofHigh Load, followed by two segments of Low Load, followed by twosegments of High Load. A 30 minute warm up at 2000 RPM and 4 bar BMEPwas also conducted prior to commencing the test procedure. This testprocedure was repeated four times for each of the lubricants tested.LSPI events were counted during the High Load segments only, usingpressure transducers placed in each of the 4 cylinders to monitor thepeak cylinder pressure. Peak pressures in the cylinder that were greaterthan 4.7 standard deviations above the mean peak cylinder pressure, ormore than 4.7 standard deviations below the mean peak cylinder pressurewere counted as an LSPI event. The results of such LSPI testing are setforth in FIG. 1.

The testing evaluated the impact of dispersant chemistry on LSPI. Asshown in FIG. 1, the amount of boron in a formulation has a strongcorrelation with the total number of LSPI counts for that oil.Specifically, as the boron ppm increases from 0, to 241, to 507, theLSPI counts surprisingly decrease from about 43, to 27, to 24. This is areduction of 40% with only about 241 ppm of boron and a reduction of 48%with about 507 ppm of boron. While the relative change in LSPI countgoing from 0 ppm to 241 ppm is larger than the relative change in LSPIcount going from 241 ppm to 507 ppm boron, the directional unexpectedbenefit of boron is still maintained. Even a boron boost of about 240ppm reduced LSPI count by an unexpected 40%. A boron source, providing 0to about 1000 ppm of boron, more preferably 0 to about 500 ppm, is thusbeneficial to the reduction of LSPI. Additionally, comparing ComparativeExample 5 with Example 2 and Example 11 further demonstrates the utilityof borated dispersants to mitigate the negative impacts of otherdispersant types. Comparative Example 5 and Example 2 showedapproximately equal LSPI event counts of 22 and 24 events respectively,while Example 2 contained only a Borated Succinimide dispersant andComparative Example 5 contained no dispersants. Furthermore, ComparingExamples 1 and 11 with Comparative Examples 1 and 2, showed that Borateddispersants significantly reduce LSPI event counts that are observed forlubricants containing non-borated dispersants alone, even at very highlevels of dispersant derived Nitrogen.

The dispersants used in the testing were further evaluated usingthermogravimetric analysis techniques (TGA). A TA instruments Q5000 TGAwas used with a platinum reference pan. Nitrogen gas was passed over thesample at 60.0 milliliters per minute. Approximately 15 mg of the sampledispersant was used in the analysis, and subjected to the followingtemperature ramp program: equilibration at 50° C., followed by atemperature ramp to 650° C. over about 1 minute, equilibration at 650°C., followed by an isothermal soak at 650° C. for approximately 15seconds. The gas was then switched to oxygen, flowing at 60.0milliliters per minute with a further isothermal soak at 650° C. for anadditional 45 seconds. Finally, the temperature was ramped from 650° C.to 750° C. over about 30 seconds, and isothermally soaked at 750° C. foran additional 30 seconds.

The results are shown in FIG. 2 and indicate that as the temperature atwhich 20% and/or 50% weight loss is achieved in a TGA measurementincreases the LSPI count decreases. The three traces on the TGA plotrepresent the three dispersant types used in this analysis.Specifically, Dispersant 1 represents High MW Succinimide Dispersant 1,Dispersant 2 represents High MW Succinimide Dispersant 2, and Dispersant3 represents the Borated Succinimide Dispersant. The 20% weight lossachieved temperatures for these dispersants are about 355° C., 344° C.,and 328° C., respectively. The 50% weight loss achieved temperatures forthese dispersants are about 406° C., 400° C., and 377° C., respectively.Surprisingly, the borated succinimide dispersant which showed a lowerLSPI count, yielded a TGA temperature at 20% and 50% weight loss whichwas higher than the non-borated succinimide dispersants which showed ahigher LSPI count.

Example B

Formulations were prepared as described in FIG. 3. All of theingredients used herein are commercially available. Group III, IV and Vbase stocks were used in the formulations.

The detergents used in the formulations were a medium TBN calcium alkylsalicylate (Calcium Salicylate 1 which contains 7.3% Ca and has a TBN ofabout 200), a low TBN calcium alkyl salicylate (Calcium Salicylate 2which contains 2.3% Ca and about 65 TBN), a high TBN calcium alkylsulfonate (Calcium Sulfonate 1 which contains 11.6% Ca and about 300TBN), a low TBN calcium alkyl sulfonate (Calcium Sulfonate 2 whichcontains 2.0% Ca and about 8 TBN), and a high TBN magnesium alkylsulfonate (Magnesium Sulfonate 1 which contains 9.1% Mg and about 400TBN). The TBN ranges are defined as: low TBN of about 0 to 100, mediumTBN of about 100 to 200, and high TBN of about 200 to as high as 600.

The dispersants used in the formulations were a borated succinimide, ahigh molecular weight succinimide (High MW Succinimide Dispersant 1) anda high molecular weight succinimide (High MW Succinimide Dispersant 2).

The remaining ingredients used in the formulations were one or more of aviscosity index improver, antioxidant, dispersant, anti-wear agent, pourpoint depressant, corrosion inhibitor, metal deactivator, sealcompatibility additive, anti-foam agent, inhibitor, anti-rust additive,and friction modifier.

Testing was conducted for formulations described in FIG. 3. The resultsare set forth in FIG. 4. Sulfated ash testing was determined inaccordance with ASTM D874. Boron, calcium and magnesium content weredetermined in accordance with ASTM D6443. Nitrogen content wasdetermined in accordance with ASTM D3228. LSPI testing was conducted forformulations in accordance with the procedures described in Example 1using the 2.0 L, 4-cylinder TGDI GM Ecotec engine.

The testing evaluated the impact of magnesium detergents and borateddispersants on LSPI. As shown in FIG. 4, the use of a borated dispersantalong with a magnesium sulfonate detergent is found to be unexpectedlybeneficial for LSPI performance. Comparative Examples 1 and 2, andExample 2 reiterate the novel findings identified in Example A withregard to the benefits of using a boron source to significantly mitigateor reduce LSPI. Examples 4 and 5, which are both formulated using amagnesium sulfonate detergent and a boron source, demonstrate excellentLSPI performance at different levels of sulfated ash. As sulfated ash isknown to be detrimental to LSPI performance, the fact that doubling thesulfated ash going from 0.8 weight percent to 1.6 weight percentunexpectedly leads to a very minimal increase in LSPI count, from 0 to2, reiterates the novel findings represented by these blends, even atextremely high ash level. Examples 4 and 5 show LSPI reductions of 100%and 95%, respectively.

Example C

Formulations were prepared as described in FIG. 5. All of theingredients used herein are commercially available. Group III, IV and Vbase stocks were used in the formulations.

The detergents used in the formulations were a medium TBN calcium alkylsalicylate (Calcium Salicylate 1 which contains 7.3% Ca and has a TBN ofabout 200), a low TBN calcium alkyl salicylate, (Calcium Salicylate 2which contains 2.3% Ca and about 65 TBN), a high TBN calcium alkylsulfonate (Calcium Sulfonate 1 which contains 11.6% Ca and about 300TBN), a low TBN calcium alkyl sulfonate (Calcium Sulfonate 2 whichcontains 2.0% Ca and about 8 TBN), a medium TBN calcium alkyl phenate(Calcium Phenate 1 which contains 5.5% Ca and about 150 TBN), and a highTBN magnesium alkyl sulfonate (Magnesium Sulfonate 1 which contains 9.1%Mg and about 400 TBN). The TBN ranges are defined as: low TBN of about 0to 100, medium TBN of about 100 to 200, and high TBN of about 200 to ashigh as 600.

The dispersants used in the formulations were a borated succinimide anda high molecular weight succinimide. The antiwear agents used in theformulations were ZDDP derived from a secondary alcohol (which contained10% by weight Phosphorus and was prepared from mixed C3 and C6 secondaryalcohols) and ZDDP derived from a primary alcohol (which contained 7% byweight Phosphorus and was prepared from C8 primary alcohols).

The remaining ingredients used in the formulations were one or more of aviscosity index improver, antioxidant, dispersant, anti-wear agent, pourpoint depressant, corrosion inhibitor, metal deactivator, sealcompatibility additive, anti-foam agent, inhibitor, anti-rust additive,and friction modifier.

Testing was conducted for formulations described in FIG. 5. The resultsare set forth in FIG. 6. Sulfated ash testing was determined inaccordance with ASTM D874. Calcium, magnesium, boron, zinc andphosphorus content were determined in accordance with ASTM D6443.Nitrogen content was determined in accordance with ASTM D3228. LSPItesting was conducted for formulations in accordance with the proceduresdescribed in Example 1 using the 2.0 L, 4-cylinder TGDI GM Ecotecengine. The testing evaluated the impact of a three additive system(i.e., detergent, dispersant and antiwear agent) on LSPI. As shown inFIG. 6, where LSPI is measured for formulations containing a non-borateddispersant and for formulations containing a mixture of non-borateddispersant and borated dispersant, the use of a borated succinimidedispersant has unique LSPI benefits over high molecular weightsuccinimide dispersant. Comparative Example 3, Example 6 and Example 10show the impact of increasing boron content on LSPI performance. As theboron content increases from 0, to 240, and to 507 ppm, the LSPI countdecreases from 46, to 27, and to 24. The benefit of boron in reducingLSPI frequency represents a significant and unexpected finding presentedin FIGS. 5 and 6. Example 8 and Example 9 showcase the uniquecombination of a magnesium sulfonate detergent with a dual dispersantsystem and a secondary alcohol derived ZDDP. The dual dispersant systemcontains a boron source. The uniqueness of this combination is shown bycomparing to Comparative Example 3, which uses a different calciumsalicylate based detergent system and has the highest LSPI counts. Theuse of magnesium sulfonate detergent, with a secondary alcohol derivedZDDP, and a borated dispersant is shown to significantly reduce, if noteliminate, LSPI. The desirable ratio of the total concentration of([Mg]+[Ca]+[Zn]+[P])/([B]+[N]_(dispersant)) is about 2.5 to 7, morepreferably from about 3.3 to 5. Comparing Example 6 with Example 12further demonstrates the utility of this approach of incorporating aborated dispersant with a secondary alcohol derived ZDDP and acombination of a magnesium sulfonate detergent with a calcium salicylatedetergent. Example 12 shows a reduction in LSPI by 98% compared toComparative Example 3.

Example D

The lubricating engine oil formulations in FIGS. 7 and 8 arecombinations of additives and base stocks and are anticipated to havekinematic viscosity at 100° C. around 7.5-8.5 cSt and high temperaturehigh shear (10⁻⁶ s⁻¹) viscosity at 150° C. around 2.5 to 2.9 cP. Thelubricating engine oil formulations of Examples P1, P2, P3 are expectedto have boron to dispersant nitrogen ratios of 0.05, 0.15, and 0.51,respectively. The total boron content in these formulations is expectedto range from 50 ppm to 800 ppm. The (Mg+Ca)/(B+Ndisp) ratio is expectedto range from 1.28 for Example P3 to 2.91 for Example P1. Similarly, the([Zn]+[P])/([B]+[N]_(dispersant)) ratio is expected to range from 0.71for Example P3 and 1.62 for Example P1. Finally, the([Mg]+[Ca]+[Zn]+[P])/([B]+[N]_(dispersant)) ratio of Examples P1, P2 andP3, is expected to be between 1.99 and 4.53. The lubricating engine oilformulations of Examples P4 and P5 are expected to have magnesiumcontent of 300 ppm to 600 ppm. Similarly the lubricating engine oilformulations of Examples P6, P7, and P8 are expected to have magnesiumcontent of about 300 ppm to 900 ppm and a magnesium to calcium ratio ofabout 0.12 for Example P6 to 1.21 for Example P8. At the same time, theTBN of these examples is varying from 6.8 for Examples P8, to P9 forExample P6. Similarly the sulfated ash content in Example P4, P5, and P6is varying from 0.3 wt % to 1.2 wt % ash. The other ratios identified inFIGS. 7 and 8 are also changing as indicated therein. The lubricatingengine oil formulations of Examples P9 and P10 are expected to havemagnesium to calcium ratio of about 0.06 and 3, respectively, at aconstant TBN. The lubricating engine oil formulations of Examples P11,P12 and P13 are expected to have zinc content ranging from about 96 ppmfor Example P13 to about 635 ppm for Example P11. The lubricating engineoil formulations of Examples P11, P12 and P13 are expected to havephosphorus content ranging from about 87 ppm for Example P13 to about570 ppm for Example P11. The ([Mg]+[Ca])/([Zn]+[P]) ratio ranges fromabout 2.5 for Example P11 to 16.5 for Example P13. The([Zn]+[P])/([B]+[N]_(dispersant)) ratio ranges from about 1 for ExampleP11 to 0.15 for Example P13. The([Mg]+[Ca]+[Zn]+[P])/([B]+[N]_(dispersant)) ratio ranges from about 3.4for c Example P11 to 2.6 for c Example P13.

Example E

The lubricating engine oil formulations in FIGS. 9 and 10 arecombinations of additives and base stocks and are anticipated to havekinematic viscosity at 100° C. around 5.5-7.5 cSt and high temperaturehigh shear (10⁻⁶ s⁻¹) viscosity at 150° C. around 2 to 2.5 cP. Thelubricating engine oil formulations of Examples P14, P15 and P16 areexpected to have boron to dispersant nitrogen ratios of 0.05, 0.15, and0.51, respectively. The total boron content in these formulations isexpected to range from 50 ppm to 800 ppm. The ([Mg]+[Ca])/([B]+[N]dispersant) ratio is expected to range from 1.28 for Example P16 to 2.91for Example P14. Similarly, the ([Zn]+[P])/([B]+[N]_(dispersant)) ratiois expected to range from 0.71 for Example P16 and 1.62 for Example P14.Finally, the ([Mg]+[Ca]+[Zn]+[P])/([B]+[N]_(dispersant)) ratio ofExamples P14, P15 and P16, is expected to be between 1.99 and 4.53. Thelubricating engine oil formulations of Examples P17 and P18 are expectedto have magnesium content of 300 ppm to 600 ppm. Similarly thelubricating engine oil formulations of Examples P19, P20, and P21 areexpected to have magnesium content of about 300 ppm to 900 ppm and amagnesium to calcium ratio of about 0.12 for Example P19 to 1.21 forExample P21. At the same time, the TBN of these examples is varying from6.8 for Example P21, to 9 for Example P19. Similarly the sulfated ashcontent in Example P17, P18, and P19 is varying from 0.3 wt % to 1.2 wt% ash. The other ratios identified in FIGS. 9 and 10 are also changingas indicated therein. The lubricating engine oil formulations ofExamples P22 and P23 are expected to have magnesium to calcium ratio ofabout 0.06 and 3, respectively, at a constant TBN. The lubricatingengine oil formulations of Examples P24, P25, and P26 are expected tohave zinc content ranging from about 96 ppm for Example P26 to about 635ppm for Example P24. The lubricating engine oil formulations of ExamplesP24, P25, and P26 are expected to have phosphorus content ranging fromabout 87 ppm for Example P26 to about 570 ppm for Example P24. The([Mg]+[Ca])/([Zn]+[P]) ratio ranges from about 2.5 for Example P24 to16.5 for Example P26. The ([Zn]+[P])/([B]+[N]_(dispersant)) ratio rangesfrom about 1 for Example P24 to 0.15 for Example P26. The([Mg]+[Ca]+[Zn]+[P])/([B]+[N]_(dispersant)) ratio ranges from about 3.4for Example P24 to 2.6 for Example P26.

Example F

The lubricating engine oil formulations in FIGS. 11 and 12 arecombinations of additives and base stocks and are anticipated to havekinematic viscosity at 100° C. around 9-11 cSt and high temperature highshear (10⁻⁶ s⁻¹) viscosity at 150° C. around 2.9 to 3.4 cP. Thelubricating engine oil formulations of Examples P27, P28, and P29 areexpected to have boron to dispersant nitrogen ratios of 0.05, 0.15, and0.51, respectively. The total boron content in these formulations isexpected to range from 50 ppm to 800 ppm. The([Mg]+[Ca])/([B]+[N]_(dispersant)) ratio is expected to range from 1.28for Example P29 to 2.91 for Example P27. Similarly, the([Zn]+[P])/([B]+[N] dispersants) ratio is expected to range from 0.71for Example P29 and 1.62 for Example P27. Finally, the([Mg]+[Ca]+[Zn]+[P])/([B]+[N]_(dispersant)) ratio of Examples P27, P28,and P29, is expected to be between 1.99 and 4.53. The lubricating engineoil formulations of Examples P30 and P31 are expected to have magnesiumcontent of 300 ppm to 600 ppm. Similarly the lubricating engine oilformulations of Examples P32, P33, and P34 are expected to havemagnesium content of about 300 ppm to 900 ppm and magnesium to calciumratio of about 0.12 for Example P32 to 1.21 for Example P34. At the sametime, the TBN of these examples is varying from 6.8 for Example P34, to9 for Example P32. Similarly the sulfated ash content in Example P30,P31, P32 is varying from 0.3 wt % to 1.2 wt % ash. The other ratiosidentified in FIGS. 11 and 12 are also changing as indicated therein.The lubricating engine oil formulations of Examples P35 and P36 areexpected to have magnesium to calcium ratio of about 0.06 and 3,respectively, at a constant TBN. The lubricating engine oil formulationsof Examples P37, P38, and P39 are expected to have zinc content rangingfrom about 96 ppm for Example P39 to about 635 ppm for Example P37. Thelubricating engine oil formulations of Examples P37, P38, and P39 areexpected to have phosphorus content ranging from about 87 ppm forExample P39 to about 570 ppm for Example P37. The ([Mg]+[Ca])/([Zn]+[P])ratio ranges from about 2.5 for

Example P37 to 16.5 for Example P39. The([Zn]+[P])/([B]+[N]_(dispersant)) ratio ranges from about 1 for ExampleP37 to 0.15 for Example P39. The([Mg]+[Ca]+[Zn]+[P])/([B]+[N]_(dispersant)) ratio ranges from about 3.4for Example P37 to 2.6 for Example P39. The concentrations of metal usedin the preceding examples are in units of total % by weight in thefinished lubricant. [N]_(dispersant) refers to the nitrogenconcentration contributed to the finished lubricant by the dispersantsonly.

PCT and EP Clauses:

1. A method for preventing or reducing low speed pre-ignition in anengine lubricated with a lubricating oil by using as the lubricating oila formulated oil, said formulated oil having a composition comprising alubricating oil base stock as a major component; and at least oneboron-containing compound, as a minor component; wherein said at leastone boron-containing compound comprises at least one borated dispersant,or a mixture of a boron-containing compound and a non-borateddispersant; and wherein the engine exhibits greater than 50% reduced lowspeed pre-ignition, based on normalized low speed pre-ignition (LSPI)counts per 25,000 engine cycles, engine operation at 2000 revolutionsper minute (RPM) and brake mean effective pressure (BMEP) at 18 bar, ascompared to low speed pre-ignition performance achieved in an engineusing a lubricating oil that does not comprise at least one borateddispersant, or a mixture of a boron-containing compound and anon-borated dispersant.

2. The method of clause 1 wherein the minor component further comprisesat least one detergent, wherein said detergent comprises at least onealkaline earth metal salt of an organic acid, and said at least onealkaline earth metal salt of an organic acid comprises at least onemagnesium salt of an organic acid.

3. The method of clause 1 wherein the minor component further comprisesat least one detergent, and at least one zinc-containing compound or atleast one antiwear agent, wherein said detergent comprises at least onealkaline earth metal salt of an organic acid, and said at least onealkaline earth metal salt of an organic acid comprises at least onemagnesium salt of an organic acid, and wherein said at least oneantiwear agent comprises at least one zinc dialkyl dithiophosphatecompound derived from a secondary alcohol.

4. The method of clauses 1-3 wherein the lubricating oil base stockcomprises a Group I, Group II, Group III, Group IV, or Group V base oil;wherein the Group V base oil comprises an ester base oil in aconcentration of 2% to 20% and having a kinematic viscosity at 100° C.of 2 cSt to 8 cSt, and the Group III base oil comprises a GTL base oil.

5. The method of clauses 1-4 wherein the boron-containing compound orborated dispersant is selected from the group consisting of a boratedsuccinimide, a borated succinate ester, a borated succinate ester amide,a borated Mannich base, and mixtures thereof; and the non-borateddispersant comprises a succinic anhydride derived succinimide orsuccinate ester with a coupling agent, wherein the coupling agentcomprises a boron-containing compound.

6. The method of clauses 1-5 wherein boron is provided to thelubricating oil by a mixture of an organic or inorganic boron-containingcompound and a borated succinimide, a borated succinate ester, a boratedsuccinate ester amide, a Mannich base ester, or mixtures thereof;wherein the borated succinimide is a mono succinimide, bis-succinimide,or a mixture thereof.

7. The method of clauses 3-6 wherein the ratio of total zinc from thezinc-containing compound and antiwear agent plus total alkaline earthmetal from the detergent divided by the total boron from theboron-containing compound and borated dispersant, in the lubricatingoil, is 9.2 to 45.

8. The method of clauses 2-7 wherein the alkaline earth metal salt of anorganic acid is selected from the group consisting of an alkaline earthmetal sulfonate, an alkaline earth metal carboxylate, an alkaline earthmetal phenate, an alkaline earth metal phosphate, and mixtures thereof.

9. The method of clauses 2-8 wherein the detergent comprises (i) atleast one of magnesium sulfonate, magnesium phenate, and magnesiumsalicylate, and mixtures thereof, and optionally at least one of calciumsulfonate, calcium phenate, and calcium salicylate, and mixturesthereof; (ii) at least one magnesium salt of an organic acid which isselected from magnesium sulfonate, magnesium carboxylate, magnesiumphenate, magnesium phosphate, and mixtures thereof; or (iii) magnesiumsulfonate, a mixture of magnesium sulfonate and magnesium salicylate, amixture of magnesium sulfonate and magnesium phenate, or a mixture ofmagnesium sulfonate and magnesium carboxylate.

10. The method of clauses 2-9 wherein (i) magnesium and alkaline earthmetal contributed by the detergent is present in the lubricating oil inan amount from 500 ppm to 5000 ppm; (ii) total base number (TBN), asmeasured by ASTM D2896, contributed by the detergent ranges from 2 mgKOH/g to 17 mg KOH/g; or (iii) sulfated ash contributed by the detergentranges from 0.4 to 1.7 wt %.

11. The method of clauses 3-10 wherein the zinc-containing compound isselected from the group consisting of zinc carboxylate, zinc sulfonate,zinc acetate, zinc napthenate, zinc alkenyl succinate, zinc acidphosphate salt, zinc phenate, and zinc salicylate.

12. The method of clauses 3-11 wherein the zinc dialkyl dithiophosphatecompound is represented by the formula

Zn[SP(S)(OR¹)(OR²)]₂

wherein R¹ and R² are independently primary or secondary C₁ to C₈ alkylgroups, provided at least one of R¹ and R² is a secondary C₁ to C₈ alkylgroup.

13. A lubricating engine oil having a composition comprising alubricating oil base stock as a major component; and at least oneboron-containing compound, as a minor component; wherein said at leastone boron-containing compound comprises at least one borated dispersant,or a mixture of a boron-containing compound and a non-borateddispersant; and wherein the engine exhibits greater than 50% reduced lowspeed pre-ignition, based on normalized low speed pre-ignition (LSPI)counts per 25,000 engine cycles, engine operation at 2000 revolutionsper minute (RPM) and brake mean effective pressure (BMEP) at 18 bar, ascompared to low speed pre-ignition performance achieved in an engineusing a lubricating oil that does not comprise at least one borateddispersant, or a mixture of a boron-containing compound and anon-borated dispersant.

14. The lubricating engine oil of clause 13 wherein the minor componentfurther comprises at least one detergent, wherein said detergentcomprises at least one alkaline earth metal salt of an organic acid, andsaid at least one alkaline earth metal salt of an organic acid comprisesat least one magnesium salt of an organic acid.

15. The lubricating engine oil of clause 13 wherein the minor componentfurther comprises at least one detergent, and at least onezinc-containing compound or at least one antiwear agent, wherein saiddetergent comprises at least one alkaline earth metal salt of an organicacid, and said at least one alkaline earth metal salt of an organic acidcomprises at least one magnesium salt of an organic acid, and whereinsaid at least one antiwear agent comprises at least one zinc dialkyldithiophosphate compound derived from a secondary alcohol.

16. A method for preventing or reducing low speed pre-ignition in anengine lubricated with a lubricating oil by using as the lubricating oila formulated engine oil, said formulated engine oil having a compositioncomprising at least one lubricating oil base stock at from 70 to 85 wt.%; and at least one dispersant at a loading to contribute from 30 to1500 ppm of boron to the formulated engine oil, wherein said at leastone dispersant comprises at least one borated dispersant, or a mixtureof a boron-containing compound and a non-borated dispersant, wherein theengine exhibits greater than 50% reduced low speed pre-ignition, basedon normalized low speed pre-ignition (LSPI) counts per 25,000 enginecycles, engine operation at 2000 revolutions per minute (RPM) and brakemean effective pressure (BMEP) at 18 bar, as compared to low speedpre-ignition performance achieved in an engine using a lubricating oilthat does not comprise at least one borated dispersant, or a mixture ofa boron-containing compound and a non-borated dispersant.

All patents and patent applications, test procedures (such as ASTMmethods, UL methods, and the like), and other documents cited herein arefully incorporated by reference to the extent such disclosure is notinconsistent with this disclosure and for all jurisdictions in whichsuch incorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.While the illustrative embodiments of the disclosure have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by thoseskilled in the art without departing from the spirit and scope of thedisclosure. Accordingly, it is not intended that the scope of the claimsappended hereto be limited to the examples and descriptions set forthherein but rather that the claims be construed as encompassing all thefeatures of patentable novelty which reside in the present disclosure,including all features which would be treated as equivalents thereof bythose skilled in the art to which the disclosure pertains.

The present disclosure has been described above with reference tonumerous embodiments and specific examples. Many variations will suggestthemselves to those skilled in this art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims.

What is claimed is:
 1. A method for preventing or reducing low speedpre-ignition in an engine lubricated with a lubricating oil by using asthe lubricating oil a formulated oil, said formulated oil having acomposition comprising a lubricating oil base stock as a majorcomponent; and at least one boron-containing compound, as a minorcomponent; wherein said at least one boron-containing compound comprisesat least one borated dispersant, or a mixture of a boron-containingcompound and a non-borated dispersant; and wherein the engine exhibitsgreater than 50% reduced low speed pre-ignition, based on normalized lowspeed pre-ignition (LSPI) counts per 25,000 engine cycles, engineoperation at 2000 revolutions per minute (RPM) and brake mean effectivepressure (BMEP) at 18 bar, as compared to low speed pre-ignitionperformance achieved in an engine using a lubricating oil that does notcomprise at least one borated dispersant, or a mixture of aboron-containing compound and a non-borated dispersant.
 2. The method ofclaim 1 wherein the minor component further comprises at least onedetergent, wherein said detergent comprises at least one alkaline earthmetal salt of an organic acid, and said at least one alkaline earthmetal salt of an organic acid comprises at least one magnesium salt ofan organic acid.
 3. The method of claim 1 wherein the minor componentfurther comprises at least one detergent, and at least onezinc-containing compound or at least one antiwear agent, wherein saiddetergent comprises at least one alkaline earth metal salt of an organicacid, and said at least one alkaline earth metal salt of an organic acidcomprises at least one magnesium salt of an organic acid, and whereinsaid at least one antiwear agent comprises at least one zinc dialkyldithiophosphate compound derived from a secondary alcohol.
 4. The methodof claim 1 wherein the lubricating oil base stock comprises a Group I,Group II, Group III, Group IV, or Group V base oil.
 5. The method ofclaim 1 wherein the Group V base oil comprises an ester base oil in aconcentration of 2% to 20% and having a kinematic viscosity at 100° C.of 2 cSt to 8 cSt, and the Group III base oil comprises a GTL base oil.6. The method of claim 1 wherein the boron-containing compound orborated dispersant is selected from the group consisting of a boratedsuccinimide, a borated succinate ester, a borated succinate ester amide,a borated Mannich base, and mixtures thereof; and the non-borateddispersant comprises a succinic anhydride derived succinimide orsuccinate ester with a coupling agent, wherein the coupling agentcomprises a boron-containing compound.
 7. The method of claim 1 whereinboron is provided to the lubricating oil by a mixture of an organic orinorganic boron-containing compound and a borated succinimide, a boratedsuccinate ester, a borated succinate ester amide, a Mannich base ester,or mixtures thereof; wherein the borated succinimide is a monosuccinimide, bis-succinimide, or a mixture thereof.
 8. The method ofclaim 1 wherein the ratio of total zinc from the zinc-containingcompound and antiwear agent plus total alkaline earth metal from thedetergent divided by the total boron from the boron-containing compoundand borated dispersant, in the lubricating oil, is 9.2 to
 45. 9. Themethod of claim 1 wherein the boron-containing compound and borateddispersant concentration ranges from 0.1 to 20 weight percent, based onthe total weight of the lubricating oil.
 10. The method of claim 1wherein the engine exhibits greater than 70% reduced low speedpre-ignition, based on normalized low speed pre-ignition (LSPI) countsper 25,000 engine cycles, engine operation at 2000 revolutions perminute (RPM) and brake mean effective pressure (BMEP) at 18 bar, ascompared to low speed pre-ignition performance achieved in an engineusing a lubricating oil containing a minor component other than the atleast one boron-containing compound, and in an amount other than theamount of the at least one boron-containing compound, in the lubricatingoil.
 11. The method of claim 2 wherein the alkaline earth metal salt ofan organic acid is selected from the group consisting of an alkalineearth metal sulfonate, an alkaline earth metal carboxylate, an alkalineearth metal phenate, an alkaline earth metal phosphate, and mixturesthereof.
 12. The method of claim 2 wherein the detergent comprises (i)at least one of magnesium sulfonate, magnesium phenate, and magnesiumsalicylate, and mixtures thereof, and optionally at least one of calciumsulfonate, calcium phenate, and calcium salicylate, and mixturesthereof; (ii) at least one magnesium salt of an organic acid which isselected from magnesium sulfonate, magnesium carboxylate, magnesiumphenate, magnesium phosphate, and mixtures thereof; or (iii) magnesiumsulfonate, a mixture of magnesium sulfonate and magnesium salicylate, amixture of magnesium sulfonate and magnesium phenate, or a mixture ofmagnesium sulfonate and magnesium carboxylate.
 13. The method of claim12 wherein, in a detergent comprising a mixture of a magnesium salt ofan organic acid and a calcium salt of an organic acid, the detergentratio of magnesium metal to calcium metal ranges from 1:0 to 1:10. 14.The method of claim 2 wherein (i) magnesium and alkaline earth metalcontributed by the detergent is present in the lubricating oil in anamount from 500 ppm to 5000 ppm; (ii) total base number (TBN), asmeasured by ASTM D2896, contributed by the detergent ranges from 2 mgKOH/g to 17 mg KOH/g; or (iii) sulfated ash contributed by the detergentranges from 0.4 to 1.7 wt %.
 15. The method of claim 2 wherein thedetergent concentration ranges from 1.0 to 6.0 weight percent, based onthe total weight of the lubricating oil.
 16. The method of claim 2wherein the engine exhibits greater than 75% reduced low speedpre-ignition, based on normalized low speed pre-ignition (LSPI) countsper 25,000 engine cycles, engine operation at 2000 revolutions perminute (RPM) and brake mean effective pressure (BMEP) at 18 bar, ascompared to low speed pre-ignition performance achieved in an engineusing a lubricating oil containing a minor component other than the atleast one boron-containing compound and the at least one detergent, andin an amount other than the amount of the at least one boron-containingcompound and the at least one detergent, in the lubricating oil.
 17. Themethod of claim 3 wherein the zinc-containing compound is selected fromthe group consisting of zinc carboxylate, zinc sulfonate, zinc acetate,zinc napthenate, zinc alkenyl succinate, zinc acid phosphate salt, zincphenate, and zinc salicylate.
 18. The method of claim 3 wherein the zincdialkyl dithiophosphate compound is represented by the formulaZn[SP(S)(OR¹)(OR²)]₂ wherein R¹ and R² are independently primary orsecondary C₁ to C₈ alkyl groups, provided at least one of R¹ and R² is asecondary C₁ to C₈ alkyl group.
 19. The method of claim 18 wherein theprimary or secondary C₁ to C₈ alkyl groups of the zinc dialkyldithiophosphate compound are derived from an alcohol selected from thegroup consisting of: 2-propanol (i-C3), 1-butanol (n-C4), 1-isobutanol(1-i-C4), 2-butanol (2-C4), 1-pentanol (primary C-5), 3-methyl-1-butanol(primary C-5), 2-pentanol (C5), 3-pentanol (C5), 3-methyl-2-butanol(C5), 1-hexanol (primary C6), 4-methyl-1-pentanol (primary C6),4-methyl-2-pentanol (C6), and 2-ethyl-1-hexanol (primary C8), andmixtures thereof.
 20. The method of claim 18 wherein the zinc dialkyldithiophosphate compound is derived at least in part from (i) a C₃ to C₈secondary alcohol, or a mixture thereof; or (ii) a mixture of a C₁ to C₈primary alcohol and a C₁ to C₈ secondary alcohol.
 21. The method ofclaim 3 wherein (i) zinc content contributed by the zinc-containingcompound or antiwear agent in the lubricating oil ranges from 500 ppm to2000 ppm; (ii) phosphorus content contributed by the zinc-containingcompound or antiwear agent compound in the lubricating oil ranges from400 ppm to 2000 ppm; (iii) zinc to phosphorus ratio in the lubricatingoil ranges from 1.0 to 2.0; or (iv) the ratio of total metals providedby the detergent to total metals provided by the zinc-containingcompound and antiwear agent is 0.8 to 4.8.
 22. The method of claim 3wherein the zinc-containing compound or antiwear agent concentrationranges from 0.5 to 5.0 weight percent, based on the total weight of thelubricating oil.
 23. The method of claim 3 wherein the engine exhibitsgreater than 75% reduced low speed pre-ignition, based on normalized lowspeed pre-ignition (LSPI) counts per 25,000 engine cycles, engineoperation at 2000 revolutions per minute (RPM) and brake mean effectivepressure (BMEP) at 18 bar, as compared to low speed pre-ignitionperformance achieved in an engine using a lubricating oil containing aminor component other than the at least one boron-containing compound,the at least one detergent, and the at least one zinc-containingcompound or antiwear agent, and in an amount other than the at least oneboron-containing compound, the at least one detergent, and the at leastone zinc-containing compound or antiwear agent, in the lubricating oil.24. The method of claim 1 wherein the lubricating oil further comprisesone or more of a viscosity index improver, antioxidant, pour pointdepressant, corrosion inhibitor, metal deactivator, seal compatibilityadditive, anti-foam agent, inhibitor, anti-rust additive, and frictionmodifier.
 25. The method of claim 1 wherein the lubricating oil is usedas a passenger vehicle engine oil (PVEO) or a natural gas engine oil.26. A lubricating engine oil having a composition comprising alubricating oil base stock as a major component; and at least oneboron-containing compound, as a minor component; wherein said at leastone boron-containing compound comprises at least one borated dispersant,or a mixture of a boron-containing compound and a non-borateddispersant; and wherein the engine exhibits greater than 50% reduced lowspeed pre-ignition, based on normalized low speed pre-ignition (LSPI)counts per 25,000 engine cycles, engine operation at 2000 revolutionsper minute (RPM) and brake mean effective pressure (BMEP) at 18 bar, ascompared to low speed pre-ignition performance achieved in an engineusing a lubricating oil that does not comprise at least one borateddispersant, or a mixture of a boron-containing compound and anon-borated dispersant.
 27. The lubricating engine oil of claim 26wherein the minor component further comprises at least one detergent,wherein said detergent comprises at least one alkaline earth metal saltof an organic acid, and said at least one alkaline earth metal salt ofan organic acid comprises at least one magnesium salt of an organicacid.
 28. The lubricating engine oil of claim 26 wherein the minorcomponent further comprises at least one detergent, and at least onezinc-containing compound or at least one antiwear agent, wherein saiddetergent comprises at least one alkaline earth metal salt of an organicacid, and said at least one alkaline earth metal salt of an organic acidcomprises at least one magnesium salt of an organic acid, and whereinsaid at least one antiwear agent comprises at least one zinc dialkyldithiophosphate compound derived at least in part from a secondaryalcohol.
 29. An engine lubricated with the lubricating engine oil ofclaim
 26. 30. A method for preventing or reducing low speed pre-ignitionin an engine lubricated with a lubricating oil by using as thelubricating oil a formulated engine oil, said formulated engine oilhaving a composition comprising at least one lubricating oil base stockat from 70 to 85 wt. %; and at least one dispersant at a loading tocontribute from 30 to 1500 ppm of boron to the formulated engine oil,wherein said at least one dispersant comprises at least one borateddispersant, or a mixture of a boron-containing compound and anon-borated dispersant, wherein the engine exhibits greater than 50%reduced low speed pre-ignition, based on normalized low speedpre-ignition (LSPI) counts per 25,000 engine cycles, engine operation at2000 revolutions per minute (RPM) and brake mean effective pressure(BMEP) at 18 bar, as compared to low speed pre-ignition performanceachieved in an engine using a lubricating oil that does not comprise atleast one borated dispersant, or a mixture of a boron-containingcompound and a non-borated dispersant.
 31. The method of claim 30wherein the formulated engine oil comprises SAE 0W-X or 5W-X wherein Xis selected from the group consisting of 8, 12, 16, 20, 30, and
 40. 32.The method of claim 30 wherein the at least one lubricating oil basestock has a kinematic viscosity ranging from 3.5 cSt to 6.0 cSt at 100C.
 33. The method of claim 30 wherein the formulated engine oil has aTBN of 4 to 10 and exhibits substantial elimination of LSPI.
 34. Themethod of claim 30 wherein the formulated engine oil has a TBN of 10 to20 and exhibits a LSPI reduction of at least 50%.
 35. The method ofclaim 30 wherein the formulated engine oil includes an ash level of from0.2 to 1.0 wt. % and exhibits a substantial elimination of LSPI.
 36. Themethod of claim 30 wherein the formulated engine oil includes an ashlevel of from 1.0 to 2.0 wt. % and exhibits a LSPI reduction of at least50%.